Here's another one I've always wondered about but, thanks to the wonders of the Intertubes, finally got a chance to hear just the other day.
A soundboard tape of The Rolling Stones 1969 free concert in Hyde Park, the one that turned into a memorial for the suddenly deceased Brian Jones.
The song is "Mercy, Mercy," the 1965 Don Covay cover that was a highlight of Out of Our Heads, the best of the group's early albums.
I'd always read that the band's performance that day was shall we say slapdash, and this excerpt kind of proves it; not exactly over-rehearsed, obviously. Although the familiar dirty sound of the Stones is still kind of overwhelming live here, at least in flashes.
Of course, the (they weren't supposed to be dead) butterflies they threw into the crowd -- which you can see in the photo -- were probably a metaphor. Not to mention the inspiration for perhaps the greatest of all WKRP in Cincinnati episodes a few years later.