Here’s one from Mark Stein’s book (I was the co-author) called
“You Keep Me Hangin’ On”: A week after Woodstock, which Fudge couldn’t do because they had a better paying gig, Vanilla Fudge played “Woodstock of the South” in Florida. Johnny Winter was on the venue and he came up to jam. Then they heard a voice off stage saying “Let’s jam, you SOBs.” It was Janis Joplin.
So Fudge, Winter, & Joplin did several songs. There is no audio nor, to my knowledge any pics.
It’s all about being in the right place at the right time, I was lucky to see the Police in 1979 in a Rensselaer Club called the Hullabaloo.
https://www.setlist.fm/venue/hullabaloo-rensselaer-ny-usa-5bd75bd4.html?page=2