Can anybody explain to me why there were so many references to "rolling stone"s in music a few decades ago? What was the causal relationship between the different rolling stones?
Examples:
The magazine Rolling Stone
The band The Rolling Stones
The Bod Dylan song Like a Rolling Stone
The Don Mclean - American Pie lyric “moss grows fat on a rolling stone”
The Jimi Hendrix - Highway Chile lyric “A rolling stone who gathers no moss”
I read somewhere that the Dylan song title comes from the Muddy Waters song “Rolling Stone.” Is that true?
Hendrix wasn’t the first, but those words (a well-known proverb that predated Hendrix by a century or two) is the basis for it all. The idea is that if you keep busy – wandering, working, whatever – you’re better off (you don’t want to be covered in moss, a metaphor for stagnation).
The proverb was used to describe people who wandered, so songwriters began to use “Rolling Stone” to mean someone who spent his life on the road, without being tied down. Blues muscians like Muddy Waters used that metaphor. Dylan probably was doing the same thing.
The Rolling Stones did name themselves for the blues tune, though I don’t know enough about it to say why. I suspect the magazine was thinking of Dylan when they chose their name.
And Mclean is using the phrase to suggest the music group – or maybe not. 
Or that if you keep moving you won’t be better off. “A rolling stone gathers no moss” is an ambiguous proverb, and the interpretation varies from place to place, generation to generation, and person to person. It all depends on whether you think gathering moss is supposed to be good or bad. Moss could represent stagnation, but it could also represent a comfortable, peaceful life or material possessions (this seems to be the case in Dylan’s “Like a Rolling Stone”). This ambiguity is probably a part of what makes the phrase so popular in song lyrics, as it can mean whatever the writer or listener wants it to mean.
The group the Rolling Stones took its name from the Muddy Waters song “Rolling Stone”.
The magazine Rolling Stone took its name from the Dylan song.
The Don McLean song refers back to the group the Rolling Stones.
All three songs, Dylan’s, Muddy Waters’s and Hendrix’s, use rolling stone as a metaphor for rootlessness, an extension of the term from the old proverb.
At least, I think that’s how it all fits together. Just goes to prove that a good metaphor is something to keep around for a rainy day.
The answer, my friend, is blowin’ in the wind.
Lots of Rock & Roll terms come from blues standards. (Like, for instance, both “Rock and Roll”, and “Rolling Stone”,) which both have biblical origins, like a lotta blues music.