Question: Which bluegrass classic by Bill Monroe was covered by Elvis Presley, and also on Alan Jackson's 2013 Bluegrass Album?
Context: Southern Flavor is the eighteenth studio album by Bill Monroe, released through MCA Records in 1988.  In 1989, the album won Monroe the Grammy Award for Best Bluegrass Recording (Vocal or Instrumental), an award currently known as Best Bluegrass Album. Bluegrass Album Band was a bluegrass supergroup, founded by Tony Rice and J.D. Crowe in 1980.  Originally, there was no intention to build a permanent group and the main reason for the collaboration was to record a solo album for Tony Rice.  They found that this cooperation could work and the result was an album called "The Bluegrass Album", released in 1981, with 5 more volumes of music to follow.  On September 5, 2012, they announced a reunion show that was held at Bluegrass First Class in Asheville, NC on February 16, 2013.  This event reunited the Bluegrass Album Band with their former manager and promoter, Milton Harkey. Bluegrass Album, Vol.  3 — California Connection is a third album by bluegrass supergroup, Bluegrass Album Band, released in 1983.  Dobroist Jerry Douglas is added to the line-up and the band includes some more country-rock to the mix, but the most part of the album consists of classics by Bill Monroe, Lester Flatt and Earl Scruggs. Bluegrass Album, Vol.  5 - —Sweet Sunny South is a fifth album by bluegrass supergroup, Bluegrass Album Band, released in 1989.  Violinist Vassar Clements is on this album replacing Bobby Hicks, and bass duties are taken over by Mark Schatz (instead of Todd Philips, who otherwise plays on all Bluegrass Album Band albums. The Lonesome Pine Fiddlers (1938- 1966) were an early bluegrass band which included such notable "first generation" bluegrass musicians as Ezra Cline, Bobby Osborne, Paul Williams, Melvin Goins, Charlie Cline, Curly Ray Cline, Larry Richardson and for a short time Jimmy Martin.  The group was started by Ezra Cline and Curly Ray Cline and was originally named "Cousin Ezra and the Lonesome Pine Fiddlers".  The Clines came from a large family consisting of musically talented people.  Ray and Charlie's father, Charlie, was a talented banjo player and the women in the family, Geraldine and Bobbi, were great singers.  For reasons unknown, Bobbi and Geraldine never joined the band on the road but often joined in at home, especially when notable Country singers, such as Bill Monroe, Lester Flatt and Earl Scruggs, and Hank Williams, came visiting.  None of them ever had a music lesson yet excelled on every instrument they touched.  Natives of the Gilbert Creek region of southern West Virginia, Cousin Ezra, along with brothers Ireland (Lazy Ned) and Curly Ray Cline, were part of the original Lonesome Pine Fiddlers from about 1938, a group that worked on radio at WHIS Bluefield, West Virginia.  During World War II, Ned was killed in action.  When the Pine Fiddlers resumed regular daily broadcasts, Charlie, who played multiple instruments, joined them on a regular basis.  Charlie returned to the Fiddlers briefly before becoming a member of Bill Monroe's Blue Grass Boys.  During 1952-1955, Charlie worked off and on with Monroe, recording some 38 songs, all on Decca.  It has been said that he played every instrument at one time or another in the Monroe group except mandolin.  Charlie spent most of 1953 back with the Lonesome Pine Fiddlers working at WJR radio in Detroit.  When Ezra brought the band to Pikeville, Kentucky, in November, Charlie rejoined Bill Monroe.  In 1954, Charlie did a session, playing lead guitar, with the Stanley Brothers and also another one on RCA with the Fiddlers, although he was not otherwise working with them at the time.  He also worked briefly as a sideman with the Osborne Brothers, although he did not record with them.  By 1958, Charlie (electric lead guitar) and his wife, Lee (electric bass), had rejoined Ezra and Curly Ray in the Lonesome Pine Fiddlers, who were experimenting with a more modern sound and working a TV show in Huntington, West Virginia, in addition to daily radio in Pikeville.  In his later years, Charlie was with the Stanley Brothers.  Curly Ray also played with the Stanley Brothers at a different time as their fiddler.  Curly Ray was one of the best fiddlers in Bluegrass.  This most talented family of musicians were the best, surpassed by none.  Finally, on October 1, 2009, The Lonesome Pine Fiddlers got their due when they were inducted into the International Bluegrass Hall of Fame at the Ryman Theater (the original home of the Grand Ole Opry).  Bobby Osborne, Melvin Goins and Paul Williams were there to receive the bands award.  In the crowd of a sold out theater was the son of Ezra Cline, Scotty Ireland Cline, who recalled being in that same theater as a child sitting on stage and watching the Fiddlers play.  (At the time, the Opry had bleachers for family just off stage).  The final act of the evening at the IBMA Awards was the playing of "Pain in my Heart" by Osborne, Goins and Williams along with a Song from the Dillards, who were also inducted the same evening. "Blue Moon of Kentucky" is a waltz written in 1946 by bluegrass musician Bill Monroe and recorded by his band, the Blue Grass Boys.  The song has since been recorded by many artists, including Elvis Presley.  In 2003, the song was chosen to be added to the United States Library of Congress National Recording Registry. Jim Nunally plays bluegrass-style, flat pick guitar with John Reischman and the Jaybirds, and with The David Grisman Bluegrass Experience.  Jim has received two Grammy award certifications and two IBMA awards for his performance on the 1996 Bluegrass Album of the Year "True Life Blues: The Songs of Bill Monroe". The Bluegrass Album is the nineteenth studio album, and the first bluegrass album by American country music artist Alan Jackson.  It was released on September 24, 2013 via Alan's Country Records and EMI Nashville.  Jackson wrote eight songs for the album.  It also includes covers of The Dillards' "There Is a Time", John Anderson's "Wild and Blue" and Bill Monroe's "Blue Moon of Kentucky".  Also included is a re-recording of "Let's Get Back to Me and You" from his 1994 album "Who I Am", marking the second time Jackson has included two versions of the same song on two different albums ("A Woman's Love" was originally recorded for "High Mileage" and was later re-recorded for "Like Red on a Rose"). True Life Blues: The Songs of Bill Monroe is a compilation album of bluegrass music released through Sugar Hill Records on October 15, 1996.  In 1997, the album won Todd Phillips the Grammy Award for Best Bluegrass Album, as the producer. The Bluegrass Album is an eponymous album by bluegrass supergroup, Bluegrass Album Band, released in 1981.  It's a collection of bluegrass standards by Lester Flatt, Bill Monroe, Earl Scruggs, Ralph Stanley and others.  Ultimately, four volumes were released, recorded between 1980 and 1985.
Answer: Blue Moon of Kentucky