Joan Baez has recorded many songs that might qualify - The Night They Drove Old Dixie Down, Oh Happy Day, Plaisirs d'Amour.

Judy Collins got some mileage out of Send In The Clowns, also the one about Pirate Jenny.

Phil Ochs did one of the early Beatles songs. It wasn't on any album he released, but after he died it came out on a cassette called The Broadside Tapes.