Maybe 90% of the stuff out there - FULL BACK DISCOGRAPHY from what I can tell

So yeah, Animal collective has a lot of stuff. Some good sources are:
https://collectedanimals.org/viewtopic.php?f=14&t=41 and https://www.discogs.com/artist/207958-Animal-Collective
but these can be redundant, so l'll try to list the entirety of the rare back discography items
I am not including live renditions of studio songs, or remixes in which the material is entirely not theirs.
These are just the rarest of rare songs, and hopefully the entirety of what is out there.
- ANIMAL COLLECTIVE - STUFF THEY PLAYED LIVE BUT NEVER RELEASED -
In 2001: you can find all of this stuff on Hollindagain and Animal Crack Box, a limited edition 2009 vinyl compilation they did. A great chunk of these songs (on ACB) were never played live, and were recorded from practice. However, on Free 103.9 Session 2001-05-09 (also their "2 Nights performance on Bandcamp) you got an untitled track. There also is an untitled track on their show in Houston 2001-05-21 (which you can find the video to here), I don't think they're the same song? It's a bit hard to tell. 
-"Don't believe the pilot" is a reoccurring song pre-sung tongs. they brought it back in 2018.
-"Guadaloops" only played once, from Dublab, 2003-07-17
-Shibuya's Nest, Tokyo 2004-04-08 has Panda and Deakin playing some unreleased songs. Great finale. 
-BBC radio 1 Breezeblock Session 2004-4-26 has unreleased song "Sleeper Factory" and Nivanna cover "Polly" along with a heart-breaking renditioning of Doggy, + a redintioning of "Covered in Frogs" 
-”Tuvin” is a song played oftentimes in the pre-sung tongs era. They brought it back in 2018. 
-”206” at La Fondation Cartier in Paris 2004-04-08 is a reworked version of “Ice Cream Factory”
-”Always You” from the Resonance FM Clearspot Sessions
-”Baby Day” played often pre-tongs era, was also on the B-side of a 7-inch vinyl pressing of “Who Could win a Rabbit” It just got put up on Spotify, by the way
-They played “Wastered” live a bit, which you can find on a rare split single with Black Dice.
-”Covered in Frogs” is a classic song played around the pre-sung tongs era. They brought it back in 2018.
-WNYC Spinning on Air 2004-07-30 has great versions of “Tuvin” and “Baby Day” but also has two songs only ever played there, “Gas Mask” and “Playpen” 
-”Sponge Luke” was only ever played at their Bowery Ballroom show 2004-08-15. Sounds almost exactly like Tangerine reef, only 14 years before.
-Their classic set at Other Music 2004-08-16 one day later has some warmups, plus “Happy Singing Band”, an untitled track after that, a good renditioning of “Covered in Frogs” and a Nirvana cover, “On a Plain.”
-”What I Do” on BBC Radio 1 2005-11-01.
- Happy Birthday, Geologist!, plus a Grateful Dead cover “We Bid you Goodnight” at Bowery Ballroom again, 2006-03-25
-”Maya", AKA "From A Beach" was played often in their early pre-MPP shows in 2007. It eventually dropped out of the lineup and remained unreleased.
-Bon Anniversaire, (happy birthday) Panda Bear! at La Maroquinerie, Paris, 2007-07-17
-Some intense shopping cart action on La Blogothèque Take-Away Show, 2007, where they play “Taste” and “Another White Singer”
-Avey Tare, Deakin, and Kria Brekkan playing one long untitled track at the Glasslands Gallery 2008-01-20
-Happy Birthday, Avey at Electric Factory 2008-04-23
-BBC Radio 1 Rob da Bank has a really beautiful remix of “Winter’s Love”. Cool version of "Taste", too.
-”The Other One,” a Grateful Dead Cover played first at the Egyptian Room 2016-10-05, and played very often during 2017. Also performed mixed with Water Curses at Terminal 5 2016-11-02 and The Bomb Factory 2016-11-16.
-Their huge performance at Coal Orgy 2017-02-24, the majority of Tangerine Reef formed, but there are two unreleased songs, “Coral Man Rock Hard” and “Flute Jam” (one of Geologist’s songs). Both were played once after, too at Festival of Disruption.
-Michael Winslow does a killer intro at Moogfest 2017-05-19
-Important set at The Music Box 2018-03-16 with Helen Gillet and Aurora Nealand. Songs played there (not counting new songs below): “Sundown with Cecil (Geologist released later through OBS), Magicians from Baltimore, Paper Forehead, A Spider Bit My Lady, What's on the Road, It's Shining, Peanut Butter Hearts, Tri Kid”
-A LIST OF NEW SONGS, PLAYED IN (2018)-2019, THAT HAVE NOT BEEN RELEASED: “DownDownDownDown, Prester John, Cherokee, 24, Kings, Strangers, Defeat (A Not Suite), Gem and I, Bolder, Dragon Slayer, Passerby, Stride Right, unknown track [Out There],” All of these played in: Cain’s Ballroom 2019-10-07, Meow Wolf 2019-10-08, Rialto Theatre 2019-10-09, Desert Daze 2019-10-11, Parachute Days 2019-10-12, Henry Miller Memorial Library 2019-10-13. Keep in mind all of these shows were played in 7 days. [“out there”] was played only in Meow Wolf.
-Happy Birthday, Noah in Atlanta Symphony Hall 2018-07-17.
- PANDA BEAR - STUFF PLAYED LIVE BUT NEVER RELEASED -
-Untitled performance: Together (with Rusty Santos) at Scandinavia House 2004-02-12
-ZDB 2004-09-27 performance “Laughed for a World full of Fantasy” and “Bonfire of the Vanities”, but you can find that on spotify. These songs were played often in shows around PP.
-untitled song at the end of his show at Freebutt 2005-01-18. recommend this one highly.
-People Party 2007 DVD
-”Lisbon Zoo” in the PBVSGR era
-Identical sets for Desert Daze 2017-10-13 and SFUCO, Libon, 2017-12-09 have 2 extra bonus beats, one after “You Can Count on Me” and the other after “Flight”
-”Comes and Goes” live at the Lodge Room 2019-2-19
- AVEY TARE WITH KRIA BREKKAN - STUFF PLAYED LIVE BUT NEVER RELEASED -
-Make sure to listen to Pullhair Rubeye backwards, of course!
-Played all of those songs live and these songs in addition: “I’ve Got Mine”, 2 untitled tracks by Kria, an untitled track [“Yelling at the Night”], “Dance to Your Daddy”, and “I’m Your Eagle Kisser”, (which appeared later on a obscure compilation under Avey). The songs can vary at shows, but their show at the First Unitarian Church 2006-11-27 has all of the unreleased songs.
- AVEY TARE - STUFF PLAYED LIVE BUT NEVER RELEASED -
-Some great unreleased songs from his Down There era, probably the best examples are at the Knitting Factory 2011-12-02. “Song for Jerome” “untitled [“sometimes”] (Mountain Game!)”, “In Photographs”, “Slow Words”, and “Death Raga.”
-With Angel Deradoorian at Family 2013-12-15: one long untitled track (“holiday drone” excerpt?)
-With Bjorn Copeland (of Black Dice) at the Getty Center 2014-06-27: one long untitled track (“Angelo Jam”?)
-Avey Tare Live at the Echo 2015-12-18: one long untitled track
-Avey Tare live at the Mothlight 2017-04-04: Really, really good. All of your favorite COHP jams except even better because he adds beats to them. An unreleased track with some block-rockin beats is “Betty Was a Doctor.” Listen to the whole thing on Bandcamp.
-Avey Tare also played some shows in 2019 with Deakin and Jeremy Hyman. No unreleased tracks, but different arrangements with drums.
-Avey Tare at the Perkins Student Center in Delaware 2019-11-16 has two unreleased and untitled songs [“Standing in Line”] and [“Beautiful Things We Find”]
- Avey Tare live at Public Records 2019-12-06 has a really good unreleased song “The Bog” along with another performance of [“Beautiful Things We Find”].
- DEAKIN - STUFF PLAYED LIVE BUT NEVER RELEASED -
-Deakin’s early shows in 2010 with a lot of the material for Sleep Cycle are a must. Unreleased songs are: “Island Chase”, “Elastik”, “2Friends (later gets the studio treatment on obscure compilation),” II”,''Guggenheim Jam, ” and  “Own Mind.” His show at Floristree 2010-04-03 is probably your best bet, but it lacks Own Mind and II, which you can find together at Music Hall of Williamsburg 2010-11-02.
-He played “Harpy” a few times, which you can find on a limited edition cassette that came with his Keep collaboration shoes.
-In 2018, Deakin played a few shows featuring three unreleased, untitled songs: [“You Know It, You Got It”], [“Sun”], and [“End”]. (he also performed his tinariwen remix “Tameyawt”.) The best example is his show at the Empty Bottle 2018-09-10 where you can find the full video here.
- GEOLOGIST - STUFF PLAYED LIVE BUT NEVER RELEASED -
- Dublab Presents: Tonalism, 356 Mission 2015-12-12: one long track plus you can see him at https://vimeo.com/149526692
-Played a lot of the songs of of his obscure cassette release Live in the Land of the Sky. Some never got released, though. "Little Boy (Geologist edit)" (which also got uploaded through his O'Brian System - see below) at the 9:30 Club 2018-05-07, ["Flute Jam"] (also from coral orgy, remember?) at that plus Will's Pub 2019-04-24. He also's got an untitled track at Gasa Gasa 2019-04-22 and played again at Will's Pub.
-ANIMAL COLLECTIVE PLUS SOLO: FEATURED OR STUFF RELEASED ONLY ON OBSCURE COMPILATIONS
-"The Kite" on compilation They Keep Me Smiling by UUAR
-"Oi Bori Suije" on Electric Gypsyland 2. You can find this on Spotify.
-"Quick as White" on Tradi-mods vs Rockers: alternative Takes on Congotronics. You can find this on Spotify.
-"In the City That Reads" on an Arto Lindsay album, credited as Avey Tare and Panda Bear
-"Forest Children Risen" credited as Avey Tare and Panda Bear
-(Animal collective remixes - https://www.discogs.com/artist/207958-Animal-Collective?type=Credits&subtype=Remix&filter_anv=0)
-Avey Tare - "Judy Biworker" on Esopus CD #4
-Avey Tare - "I'm Your Eagle Kisser" on Living Bridge
-Avey Tare's Slasher Flicks - "Visit the Dojo (Slasher Flicks Demo)" on compilation Our First 100 Days.
-Avey Tare appears on album Ramu by Mickey Hart. You can find this on Spotify.
-Avey Tare & Deakin produced Tickley Feather's album Tickley Feather 1 2 3
-(Panda Bear remixes: https://www.discogs.com/artist/218809-Panda-Bear?type=Credits&subtype=Remix&filter_anv=0)
-Panda Bear - an untitled track on Visionaire No. 53: Sound
-Noah Lennox and Paul Maroon - "I Don't Need A Crowd"
-you can find all of panda bear's features below on Spotify except for Boneless 
-Panda bear and Pantha Du Prince - "Stick to My Side"
-Zomby feat. Panda Bear - "Things Fall Apart"
-The Notwist - "Boneless (Panda Bear Remix) - Panda adds his vocals, so more like an original.
-Teebs feat. Panda Bear - "Studie" - top-level Panda. A classic.
-(Panda bear helped produce and lent vocals to albums When I Get Home (by Solange) and All Things Being Equal (by Sonic Boom))
-Panda bear featured on "Killing the Vibe" by Ducktails
-Panda bear featured on "Doing it Right" by Daft Punk, but you knew that.
-Panda bear featured on "Pyjama" by Teenage Fantasy
-Panda bear featured on the album Zushi by Dean Blunt
-Noah Lennox featured on "Walkabout" by Atlas Sound
-Panda Bear featured on "Gameday Continues" on the album HBCU Gameday by Sporting Life
-(Panda Bear backup vocals of "Anna", by Taken By Trees)
-Panda bear produced Maria Reis - A Flor da Urtiga
-(Deakin remixes - https://www.discogs.com/artist/2196555-Deakin?type=Credits&subtype=Remix&filter_anv=0 plus "Boundary Waters" by Palms, but as Josh Dibb)
-(Josh Dibb and Dave Portner contribute vocals and drums on tracks "Om Mane Padme Hum" and "Storm Worship" (respectively) by Prince Rama.)
-Deakin contributes an untitled track to a compilation called Get Weird (the compilation, not the track) - "2Friends" but with studio treatment.
-Deakin and Geologist - "Seeing Twinkles" on mix Music For Plants
-Geologist contributed "Man o' War" to a Coral Morphologic soundtrack
FOR NON-HEADS: OFFICIALLY RELEASED STUFF THAT IS RARE AND DIDN'T MAKE IT TO SPOTIFY
-Automine - Paddington Band EP - earliest release in 1996 featuring some members of the band.
-"Wastered" - split single with black dice. Available on Bandcamp
-"Purple Bottle/Polly" - white label limited release with "purple bottle (stevie wonder version)" and Nirvanna cover "Polly" on the B-side. 
-Keep E.P - Great stuff released on a limited edition cassette with custom made shoes. "Jailhouse" got put on Transverse Temporal Gyrus, "The Preakness" got shoehorned into not only a tomboy 4XLP deluxe edition but got remixed rave style for Crosswords E.P. I don't think "Country Report" got used anywhere. And last but not least, "Call Home (Buy Grapes)" was not used for anything else. Listen on Bandcamp
-a (very) limited cassette release of "Micheal Remember / Danny's jam" Uses the same sound palate as Painting With, but is more improvisational. Listen to it on youtube.
-Something that popped up on bandcamp: https://anmlcollectve.bandcamp.com/track/ballad-of-reverend-war-character-silver-jews-cover-2
-Animal Crack Box - extensive collection of early live recordings. Released in 2009. Listen to it on YouTube.
-ODDSAC - 2010 visual album. original / AI 4K Upscaling
-Avey Tare - Split Series - With David Grubbs - Bandcamp (Of Avey's side)
-Avey Tare - Pandemic Dream 4 - Bandcamp
-Avey Tare - Tipped In Hugs / Dog Says Goodbye - 7 inch released with deluxe version of COHP vinyl. Bandcamp
-Avey Tare joined Eric Copeland for a duo called Terrestrial Tones. 3 albums - Blasted, Obored/Circus Lives, Dead Drunk (Spotify)
-PANDA BEAR'S 1999 SELF-TITLED ALBUM - If you haven't heard of this, listen to it as soon as possible.
-Noah Lennox and Scott Mou formed Jane. 3 albums: Paradise, Coconuts, Berserker (Spotify)
-Avey Tare's Slasher Flicks but you already knew that
-Grass EP is on Spotify (they just put it up), but the DVD that came with it isn't! It features the music videos for "Who Could Win A Rabbit" and "Grass", but also a rare video of "Fickle Cycle" and video collage "Lake Damage"
-Deluxe versions of Centipede HZ on vinyl came with a bonus DVD of them live at prospect park. This DVD also has a hidden video. https://www.youtube.com/watch?v=3u_GrN0RYOs&list=PLmExGAfaAIROU2geyjOEHMRprerRPIko4&index=27
-Deakin - "Harpy" cassette that came with its own shoes: "Harpy (red)" and "Harpy (blue)" - very, very good songs
-Geologist - Live in the Land of the Sky - cassette
-EXCLUSIVE SONGS ON THEIR CENTIPEDE HZ RADIO TRANSMISSIONS
-Avey Tare (with Angel Deradoorian) – "Excalibur " - listen to it right now.
-Avey Tare (with The Deradoorian Sisters) – “Mr. Funny Man” - listen to it right now.
-Avey Tare – “Bobby’s Loop”
-Panda Bear – “Soft Serve Rip Curl” (Instrumental)
-Panda Bear – “Principe Real” (Instrumental)
-Animal Collective – “Practice” - it is "Mercury Man" they are practicing
-SONGS ON GEOLOGIST'S RADIO SHOW, "THE O'BRIAN SYSTEM" - Geologist solo material (!)
-GEOLOGIST -Unused Coral Demo 1
-GEOLOGIST - Unused Coral Demo 6
-GEOLOGIST - Unused Coral Demo 13
-AVEY TARE - West Palm Beach (Palace Cover)
-GEOLOGIST - Tonalism Edit (Live: 356 Mission, LA, CA 12/12/15) (also live)
-GEOLOGIST - DSXIO (2 separate times in the same episode)
-GEOLOGIST - IOXDS
-GEOLOGIST - IOXIO
-GEOLOGIST - Tiles
-GEOLOGIST - Coral Demo 11
-GEOLOGIST - Sundown With Cecil
-GEOLOGIST - How Dare Snakes?
-GEOLOGIST - Little Leo
-CAMPFIRE SONGS - Bleak Midwinter
-GEOLOGIST - Coral Demo 7
-GEOLOGIST & KYLE SIMON - The Sirens
-CORAL MORPHOLOGIC - Transmission (not technically Animal Collective...)
-GEOLOGIST - ZoomBloom (also on Live in the Land of the Sky)
-AVEY TARE - Grassy Grain Coral Demo
-AVEY TARE - Blooming Coral Demo
-AUTO MINE - Penny Painting (Live) (Paddington EP)
-GEOLOGIST - Steam Tunnels 99
-GEOLOGIST - Song 1: Eyes 2
-ANIMAL COLLECTIVE - Pillows & Petals (Live @ The Parkway Theater, Baltimore, MD 9/29/17)
-GEOLOGIST - Song 1: Eyes 3
-ANIMAL COLLECTIVE - House (HBDMPP Edit) 
-ANIMAL COLLECTIVE - Crispy Pops (Live 2009) (edits of MPP era songs)
-GEOLOGIST - Stretching Songs For Spring (also on New Psycho Actives)
-NEW PSYCHO ACTIVES - Summer Blaze (also on New Psycho Actives)
-NEW PSYCHO ACTIVES - Autumn Rites (also on New Psycho Actives)
-AVEY TARE & BJORN COPELAND - AngelenoJam (also live)
-GEOLOGIST & ROBERT MILLIS - Distant Duo
-MISCELLANEOUS OTHER STUFF
-Panda Bear - "Song for Ariel" - Guys eyes, earlier version 
-Panda Bear - The original and updated versions of "Atiba Song"
-Panda Bear - "Swallow at the Hallow"
-New Psycho Actives Part 1: Avey Tare - "Tape Chants for Winter", Geologist - "Stretching Songs for Spring". Part 2 - "Autumn Rites, "Summer Blaze"
-Animal Collective - "Suspend the Time (feat. Ami Dang)" - collaboration with an ocean project. You can get the mp3 if you sign up. https://ocean-acidification.org/
Down There interview -https://vimeo.com/15826696
Slasher flicks full album visual stream - unlisted! -https://www.youtube.com/watch?v=f6H4OGARJMs
geo on the hurdy gurdy -https://www.youtube.com/watch?v=EogcRM16Z-U
tangerine reef video -https://www.youtube.com/watch?v=KCup2fmAUuk
buoys promo -https://www.youtube.com/watch?v=-WBiOcmdxXQ
plus Panda Bear's Alien Promo for PBVSGR. Not going to link b/c NSFW warning, viewer discretion advised
pbvsgr documentary -https://www.youtube.com/watch?v=JNkxDP8WviM
pbvsgr -https://www.youtube.com/watch?v=g2iFOaAkl34
pbvsgr -https://www.youtube.com/watch?v=nYL2jY-SVa8
Micheal winslow on moonjock -https://www.youtube.com/watch?v=gBaXq3Sr3G0
-Avey Tare and Deakin - "Porch Life" Improvised Set https://www.youtube.com/watch?v=L75rwoC7Rx0
-Visuals for their ODDSAC 10th anniversary DJ sets.
-Avey Tare "Ocean" - exclusive song (plus sound effects) on his website where he has a puzzle for you. https://www.aveytare.com/main/
-John Cale featuring Animal Collective (live) - "There She Goes" - good beats: https://www.youtube.com/watch?v=G6Sc2gccVJA
-https://soundcloud.com/anmlcollective/dont-think-twice-its-all-right-animal-collective-remix
-You can find 2001 shows on Youtube. Long transitions and lots of screaming, so new experience instead of just renditions of songs.
-Animal collective did a great mix of Shabazz Palaces's #CAKE - https://www.youtube.com/watch?v=bp-T12nitfo
-Avey Tare - "Fly" - https://www.youtube.com/watch?v=HIyLooHJeKc
-Edgar is real: https://www.youtube.com/watch?v=0lws6P53wVo
-"Grass" acoustic version :) https://www.youtube.com/watch?v=kQ96BXVXo70
https://www.youtube.com/watch?v=kbgrTmho7VE
https://www.reddit.com/r/AnimalCollective/comments/m1ps98/i_regret_nothing_shitpost/
thank you. If you find some extra deep cut, please comment or add it.