Lots of them out there; I've about concluded that if a song "has it" in every way, you can go almost anywhere with it, so long as you treat it with respect, without hurting it.
Roberta Flack's rendition of "The First Time Ever I Saw Your Face".
Joan Baez treatment of "Lily, Rosemary & the Jack of Hearts", which I had never heard until someone here linked it a few days ago.