As far As I know it is not legal . My brothers had permission to dig on private land back a few years ago . The Creek Indians here in Alabama found out about it . My next older brother nearly went to jail over it . It cost him a lot of money to stay out . It may have been because they were digging a HISTORIC site . Trade beads , gun parts , rum bottles , copper , silver .....ect. I do not know of any pay digs here .
The Tennessee Valley Authority and water patrol will also ticket you for surface collecting on the Tennessee River . There is a petition going around in hopes of changing that .