(I'm doing this from memory, so I might have some of the details wrong)
Elliot Landy (who shot promo photos for The Band, Van Morrison, etc.) was commissioned to do the cover shot for Nashville Skyline, Dylan's first "country" album. He handed him George Harrison's (or Johnny Cash's, depending on who tells the story) guitar and took a handful of pictures. The two started goofing off, with Dylan suggesting weird angles and positions. Landy just kept clicking his camera, at one point kneeling down on the ground and shooting up at his subject. That's the shot that made the cover.
Hell, that was more boring and pointless than I thought, but it's the only "cover story" I know.
