Occasional Rain [Cadet, 1972]
What Color Is Love [Cadet, 1973]
I Just Can't Help Myself [Cadet, 1974]
The series of Cadet label albums that remain his perennial classics. Excellent songwriting and singing coupled with baroque, occasionally psychedelic arrangements and stellar musical backing, all pretty much defying categorization yet today. Alternately soulful, folky, jazzy, pop, but never really any of the above. These would probably be the ones to start with.