As has been mentioned, you must visit Elvis' house, Graceland, in Memphis. Twenty years from now, you will not forgive yourself if you miss this sacred shrine. A few years ago a visitor found a toenail clipping in the shag carpet - A PIECE OF ELVIS! (I have a series of photographs of my mother, posed in every room of Graceland. It's the best thing my sister and I have to remember her.)
Some miles south of Memphis, along highway 61 in Mississippi, is the cross-roads where Robert Johnson (the great bluesman and essentially the inventor of rock&roll) is said to have traded his soul to the devil for his guitar skills. This place is also sacred and ranks with Lourdes or Jerusalem as holy.
Have a nice ride.