While traveling through South Mississippi, I saw a large area of these beautiful wildflowers along I-59, so I had to stop. The flowers were growing on 4 or 5 foot stalks,and the stalks were growing close together. If you can ID this flower, please post it as a comment.
EDIT: Thanks to someone on gardenweb.com, the flower has been identified as a Showy Crotalaria (Crotalaria spectabilis).