National Cornbread Festival https://nationalcornbread.com
Most folks who aren't local (I was local) drive in from a bit out...
Also in the area (in addition to those mentioned above):
Marion County Park https://www.facebook.com/marioncountypark/
Hales Bar & Marina has a campground https://halesbarmarina.com
Camp Chet (in the "Pocket" on top of Whitwell Mtn) https://www.campchet.com/OutpostRV
A bit of a drive will be:
Fall Creek Falls SP https://www.tnstateparks.com/parks/fall-creek-falls
South Cumberland SP (small RVs, no hookups and no gasoline generators allowed, LOTS of shade, really better suited for a truck camper than an RV) https://tnstateparks.com/parks/campground/south-cumberland
Harrison Bay SP (east side of Chatt) https://www.tnstateparks.com/parks/harrison-bay
Chester Frost County Park (2 day minimum stay) https://parks.hamiltontn.gov/facilities/facility/details/chesterfrostpark-1
Tim's Ford SP (50 amp RVs are better off at the Fairview cg) https://www.tnstateparks.com/parks/tims-ford
Old Stone Fort SP https://tnstateparks.com/parks/old-stone-fort