[4] Kelley should not be confused with the similarly named Kevin Kelly, another American session musician who played piano for Joan Baez during the Rolling Thunder Revue and guested on albums by Tim Buckley, Judee Sill, Bryn Haworth, and The Babys during the 1970s.
[6] In 1965, after returning to civilian life, he became the drummer with one of the earliest Los Angeles folk rock bands, the Rising Sons, a group that also included guitarists Ry Cooder and Taj Mahal.
[6] It was while he was working at the clothing store that Kelley's cousin, Chris Hillman, who was the bass player with the successful L.A. folk rock and psychedelic band the Byrds, asked him to join the group in January 1968.
[6][9] The Byrds had recently been reduced to a duo following the October 1967 firing of rhythm guitarist David Crosby[10] and the December 1967 departure of the band's original drummer, Michael Clarke.
[16] In addition to participating in the recording of Sweetheart of the Rodeo, Kelley was also with the Byrds when they made their infamous appearance at the Grand Ole Opry in Nashville on March 15, 1968, where the band was met with booing and heckling from the audience, due to their association with the hippie counterculture.
Following the release of Sweetheart of the Rodeo, Kelley was dismissed from the Byrds in September 1968,[3] largely due to pressure from the group's new lead guitarist Clarence White, who had come on board as a replacement for Gram Parsons in July 1968.
[19] Between 1969 and 1973, Kelley found work as a session musician, guesting on albums by John Fahey, Phil Ochs, Frank Kinsel, Jerry Jeff Walker, Judee Sill, Jesse Wolff & Whings, and Michael Cohen.