Pink Floyd - The Gold It's in The...
If you only know Pink Floyd for Dark Side of the Moon, Wish You Were Here and The Wall, there is an entire world of Floyd you are missing. Do yourself a favor and check out some of the following: Piper at the Gates of Dawn, Saucerful of Secrets, Atom Heart Mother, Ummagumma, Meddle, and the soundtracks to More and Zabriskie Point.
The track embedded above (pardon the freeze frame video) is an example of probably the most straight-forward rock song Pink Floyd ever did, from another soundtrack "La Vallee", that was retitled Obscured by Clouds. I've never seen the film, which is French, but there are some real buried gems by the band on this CD.
Also, the first two albums in the list above are very much a product of the 60's psychedelia movement. Check out wikipedia for some information on Syd Barrett to learn of his influence on the early Floyd sound.