There was a Joni mention from the 4th Season of Ellen in an episode called Ellen Unplugged. This episode involves Ellen going to music camp. When Ellen meets guest star David Crosby, she doesn't believe it's really him, and introduces herself and her friends by saying, "Yeah, and I'm Joni Mitchell and this is Peter, Paul and Mary."
Queen Latifah, Aaron Neville, Bonnie Raitt and Cheryl Crow also guest star in this episode.
Original Air Date: Wednesday, February 5, 1997 on ABC