I missed the part that it could be more than three. Still:

The Beatles did Elvis's "That's All Right, Mama"
Elvis did Sinatra's "My Way"
Sinatra did The Beatles' "Something"

Challenging myself to memory only, I'm stumped, too!

I first thought Hendrix, since he covered some stuff like The Beatles on their release day. Also did "Sunshine of Your Love" while Clapton covered "Little Wing."

Tough because so many are multigenerational, requiring a rare Johnny Cash type who covers the young. Probably have better luck with peers, like old bluesmen or British Invasion.