Question: Who produced the Sturgill Simpson album that was nominated for a Grammy Award for Best Americana Album?

Context paragraphs:
Sturgill Simpson: John Sturgill Simpson (born June 8, 1978) is an American Grammy Award-winning country music and roots rock singer-songwriter.  As of August 2017, he has released three albums as a solo artist.  He released two albums independently, "High Top Mountain" in 2013 and "Metamodern Sounds in Country Music" in 2014.  His second album is notable for being nominated for a Grammy Award for Best Americana Album, being listed 18th on "Rolling Stone's" "50 Best Albums of 2014," and also being named among "NPR's 50 Favorite Albums of 2014."  His third studio album, "A Sailor's Guide to Earth", was released on Atlantic Records and was Simpson's first major-label release, later earning him Best Country Album at the 59th Grammy Awards while also being nominated for Album of the Year.

Grammy Award for Best Americana Album: The Grammy Award for Best Americana Album is an honor presented to recording artists for quality albums in the Americana music genre at the Grammy Awards, a ceremony that was established in 1958 and originally called the Gramophone Awards.  Honors in several categories are presented at the ceremony annually by the National Academy of Recording Arts and Sciences of the United States to "honor artistic achievement, technical proficiency and overall excellence in the recording industry, without regard to album sales or chart position".

Willie and the Wheel: Willie and the Wheel is an album from American country music artists Willie Nelson and Asleep at the Wheel.  This album was released on February 3, 2009, on the Bismeaux Records label and was nominated for the Grammy Award for Best Americana Album.

Grammy Award for Best Contemporary Folk Album: The Grammy Award for Best Contemporary Folk Album was awarded from 1987 to 2011.  Until 1993 the award was known as the Grammy Award for Best Contemporary Folk Recording.  In 2007, this category was renamed Best Contemporary Folk/Americana Album.  As of 2010 the category was split into two categories; Best Contemporary Folk Album and Best Americana Album.

Brandi Carlile: Brandi M. Carlile (born June 1, 1981) is a Grammy nominated American americana and folk rock singer-songwriter.  Born in Ravensdale, Washington, she dropped out of high school to pursue a career in music, teaching herself piano and guitar.  Her first commercial album, "Brandi Carlile", was released to critical acclaim but to limited commercial success.  Carlile garnered wider recognition for her 2007 single "The Story", from the album of the same name, was a greater commercial success. " The Story" turned gold in 2017, selling 500,000 copies to date.  Carlile's latest album "The Firewatcher's Daughter" earned her a Grammy Nomination for Best Americana Album and peaked at no. 9 in Billboard 200.

Tin Can Trust: Tin Can Trust is a 2010 album by the band Los Lobos, and is the band's first collection of new original material since 2006.  It features rock 'n' roll, blues, two Spanish language tracks, and a Grateful Dead cover song.  The album was nominated for a Grammy Award for Best Americana Album.

The Firewatcher's Daughter: The Firewatcher's Daughter is the fifth studio album by Brandi Carlile, released on March 3, 2015 on ATO Records.  It was nominated for a Grammy Award for Best Americana Album at the 2016 awards.

Wilco (The Album): Wilco (The Album) is the seventh studio album by American alternative rock group Wilco which was released June 30, 2009.  Prior to release, Wilco streamed the album on their website.  The album was nominated for a Grammy Award for Best Americana Album.

Something More Than Free: Something More Than Free is the fifth studio album by Jason Isbell.  It was produced by Dave Cobb, who also produced Isbell's last record, "Southeastern".  The album received the Grammy Award for Best Americana Album at the 58th Annual Grammy Awards.

Metamodern Sounds in Country Music: Metamodern Sounds in Country Music is the second studio album by American country music singer-songwriter Sturgill Simpson.  The album was produced and engineered by Dave Cobb and was released on May 13, 2014, through High Top Mountain/Thirty Tigers & Loose Music (Europe).

Supporting paragraphs: Sturgill Simpson Metamodern Sounds in Country Music
Answer: Dave Cobb