There's a good "legend" in the Deep Blues book which places Robbie Robertson
and the band playing music with Rice Miller a few weeks before he passed
away in 1965.
Levon Helm also tells the story. He said that Sonny Boy was spitting blood
into a cup the whole time they played. (He was tubercular, that's what
killed him I guess.)
He also said the local cracker cops showed up and told them to get out and
not visit nor congregate with Black people again.
Bob Dylan wrote that he got to jam with Sonny Boy and John Lee Hooker in a
hotel room in NYC in the early 60's, and that Sonny Boy told him he played
too fast.