Ones that spring immediately to mind:
   
   La Bottine Souriante a few times
   The Red Clay Ramblers
   Pete Seeger and Arlo Guthrie (together a couple of times)
   Tom Paxton
   Eric Bogle
   The New Lost City Ramblers
   The Del McCoury Band
   The Greenbriar Boys
   Peggy Seeger
   Natalie McMaster
   April Verch
   Stan Rogers
   Garnet Rogers
   Gamble Rogers