Sam Bush, Sheryl Crow, Buddy Miller and Billy Bob Thornton will be special guests at Levon Helm’s Wednesday night (Sept. 17) concert at the Ryman Auditorium in Nashville. Helm’s concert is the kickoff for the Americana Music Festival and Conference, which runs through Saturday night. His most recent album, Dirt Farmer, won a Grammy for best traditional folk album of the year. He is also nominated for three Americana Honors. The awards ceremony will be held on Thursday (Sept. 18) at the Ryman.