A tape featuring four songs by a teenage Bob Dylan could fetch up to $100,000 (£53,000) when it is sold at auction in Dallas next month.
Bob Dylan is one of the 20th Century's most influential artists
The recordings were made in Minnesota in the late 1950s by Dylan and childhood friend Ric Kangas.
The music legend, then called Robert Zimmerman, sings on three songs and plays guitar on the fourth.
Kangas discovered the tape a few years ago but was unable to play it before finding an old-style tape recorder.
Two of the tracks, I Got Trouble and I Got A New Girl, featured in Martin Scorsese's 2005 Bob Dylan documentary, No Direction Home.
The third, The Frog Song, hints at Dylan's later vocal style: "He kind of sings like a frog," said Kangas.
The pair met after Dylan watched Kangas perform in a high school talent show. For the next few months they often sang and played songs for each other, leading to the recording session.
Dylan later moved to Minneapolis and New York, where legendary talent scout John Hammond gave him a record deal.
Kangas, a former Elvis impersonator, says he kept in touch with his childhood friend, although their last meeting was backstage after a show in Memphis in 1974.
The tape goes on sale at the Heritage Auction Galleries in Dallas, Texas, in October.
A publicist said Dylan, 65, had no comment.