I’ve always loved this particular tune. I grew up listening to the Allman Brothers version, and count it as one of my favorites. Like a lot of great rock&roll tunes, though, it has an interesting past. You see, it isn’t just that the old rock bands were inspired by blues. Some of their greatest hits were cover tunes. According to the almighty wiki, this was first recorded by Elmore James who didn’t release it for several years. Later Sonny Boy Williamson put out a couple different versions. I think my own favorite would be the Williamson version with Buddy Guy on guitar.