An undiscovered trove of lyrics, letters and poems from late country icon Johnny Cash will come to life on April 6 on the album Johnny Cash: Forever Words. The collection will transform phrases left behind by the Man in Black into songs by late Soundgarden singer Chris Cornell, Ruston Kelly & Kacey Musgraves, Rosanne Cash, Alison Krauss & Union Station, Kris Kristofferson & Willie Nelson, Brad Paisley and many more.

The 16-track album was compiled using what the albums' co-producer, Cash's son John Carter Cash, described as a "monstrous amassment" of material left behind by Johnny and June Carter Cash after their deaths. The handwritten letters, documents and poems were penned by Cash over the course of his life and shaped into songs over the past two years by John Carter Cash and co-producer Steve Berkowitz. Mostly recorded at The Cash Cabin Studio in Hendersonville, Tennessee, the collection is the musical companion to the 2016 best-selling book Forever Words: The Unknown Poems, a collection of unpublished writings edited by Pulitzer Prize-winning poet Paul Muldoon and curated by John Carter and Berkowitz. Among the other contributors: Jewel, Jamey Johnson, The Jayhawks, T. Bone Burnett, Robert Glasper and John Mellencamp.

According to a release announcing the project, many of the songs on the album were directly inspired by the material in the book, with others drawn from other sources of Cash's unpublished writings. "The tone of the album is established with the opening track 'Forever/I Still Miss Someone' featuring Kris Kristofferson reciting the last poem Cash ever wrote alongside guitar accompaniment from Willie Nelson, both lifelong friends of Johnny," reads a statement. "Continuing the close-to-home theme, the music then transitions to the deeply personal 'To June This Morning,' a letter Johnny wrote to his wife, June Carter Cash, now interpreted by real-life couple Ruston Kelly and Kacey Musgraves."

In one of the more emotionally wrenching moments, 21 years after Cash recorded his iconic cover of Soundgarden's "Rusty Cage" for his Grammy-winning Unchained album, Cornell -- who committed suicide in May 2017 -- is heard singing "You Never Knew My Mind," which is described as "setting some of Cash’s own poignant and introspective words to original music on one of Cornell’s last solo recordings." The song represents one of Cornell's final known recordings.

"Determining the artist for each song was truly a matter of the heart," says John Carter Cash. "I picked the artists who are most connected with my father, who had a personal story that was connected with Dad. It became an exciting endeavor to go through these works, to put them together and present them to different people who could finish them in a way that I believed that Dad would have wanted."

Cash's eldest daughter, Rosanne, interprets "The Walking Wounded," which marks just the second time in her career that she's collaborated on a recording with her half-brother John Carter Cash. The album's co-producer also collaborates with his half-sister Carlene on "June's Sundown." The album also features the first new recording in 6 years from Grammy-winning bluegrass supergroup Alison Krauss & Union Station. You can pre-order the album here.

Track listing for Johnny Cash: Forever Words:

"Forever/I Still Miss Someone" - Kris Kristofferson and Willie Nelson

"To June This Morning" - Ruston Kelly and Kacey Musgraves

"Gold All Over the Ground" - Brad Paisley

"You Never Knew My Mind" - Chris Cornell

"The Captain's Daughter" - Alison Krauss and Union Station

"Jellico Coal Man" - T. Bone Burnett

"The Walking Wounded" - Rosanne Cash

"Them Double Blues" - John Mellencamp

"Body on Body" - Jewel

"I'll Still Love You" - Elvis Costello

"June's Sundown" - Carlene Carter

"He Bore It All" - Daily and Vincent

"Chinky Pin Hill" - I'm With Her

"Goin', Goin', Gone" - Robert Glasper featuring Ro James, and Anu Sun

"What Would I Dreamer Do?" - The Jayhawks

"Spirit Rider" – Jamey Johnson

Check out a trailer for the album below, with moving black and white footage from the sessions and testimonials from Paisley and Rosanne Cash: