Bjork, Prince, James Taylor and Elvis Costello are among the artists who have recorded covers for "A Tribute to Joni Mitchell," due in the spring via Nonesuch. The 12-track set also boasts contributions from Sarah McLachlan, k.d. lang, Emmylou Harris and Sufjan Stevens.

In related news, Billboard.com has learned that Mitchell has been recording original material at a Los Angeles studio in recent weeks. It is unknown in what form she plans to release the music; she angrily announced she was quitting the music business in 2002 after her last album, "Travelogue."

"A Tribute to Joni Mitchell" comes concurrently with 429 Records' "Endless Highway: A Tribute to the Band," due Jan. 30. That projects boasts covers from Death Cab For Cutie, My Morning Jacket, Jack Johnson and Widespread Panic, among others.

Here is the track list for "A Tribute to Joni Mitchell":

"Free Man in Paris," Sufjan Stevens
"Boho Dance," Bjork
"Dreamland," Caetano Veloso
"Don't Interrupt the Sorrow," Brad Mehldau
"For the Roses," Cassandra Wilson
"A Case of U," Prince
"Blue," Sarah McLachlan
"Ladies of the Canyon," Annie Lennox
"Magdalena Laundries," Emmylou Harris
"Edith and the Kingpin," Elvis Costello
"Help Me," k.d. lang
"River," James Taylor