Sly and Family Stone, a band that electrified Woodstock, was perhaps the primary bridge between funk and rock and roll. The story is one of great talent, great intentions (listen to the lyrics) and–for a while–great success. It fell apart in the early 1970s, and Sly Stone’s comeback appears to have run out of gas. All Music has a great bio.
Here is If You Want Me to Stay introduced by Wolfman Jack on Midnight Special.