Tenn. Code Ann. § 11-3-301

It is the legislative intent that people who use the state parks be given the opportunity to voluntarily contribute to the maintenance, renovation, promotion, expansion, recreational and educational programs, and operations of such parks. Each state park shall provide a collection point, box or other suitable arrangement at which park users may make donations to the state park fund, with the exception of those state parks that the commissioner of environment and conservation may certify as not being suitable for the collection of such fee.