Amazing talent. The Beverly Hillbillies theme was performed by the duo of Lester Flatt & Earl Scruggs.
Both were great musicians. The The Ballad of Jed Clampett on TV is played by them but not sung by them. However they do sing it on albums. Another guy Jerry Scoggins sang it for TV. The writter of the series Paul Henning wrote the song.
There is a great video on You Tube with Earl Scruggs, Randy Scruggs, Chet Atkins, Daune Eddy, Vince Gill, and others all playing Lonesome River.