I just found out about a place in Shelbyville looking for performers every Friday and Saturday nights 5:30-8:00. They do not pay the performers but you do get to eat the buffet meal for free.  I think they like acoustic based music and have had several bluegrass and gospel performers come out to perform.  There is a sound system set up with 2 microphones. They also pass the tip bucket and you can sell Merchandise.

Here is the contact info:
Parkway Cafeteria
223 Lane Parkway
Shelbyville, TN
931-684-7288