Reba McIntyre's remake of Bobby Gentry's "Fancy"
Mr Bojangles - Nitty Gritty Dirt Band cover

"Hound Dog" was written as an r&b song for Big Mama Thornton but totally reworked as a rockabilly song by Elvis, whose version is thought of as the "definitive" one.

PP&M's remake and reworking of Pete Seeger's "If I Had A Hammer"

Jeff Buckley's cover of Leonard Cohen's "Hallelujah"

Either Rod Stewart's or Sheryl Crow's version of Cat Stevens' "The First Cut Is The Deepest."