Southeast resident here. I know you are looking for free options, but if you are willing to do some research you can find some pretty great extremely cheap option. Your local library has basically a phone book of all the campsites in america. We took it on a 7-week roadtrip. If the idea is less of a road trip, more of living as cheaply as possible wherever you can familiarize yourself with that series of books 'best campsites in . . ." "Best hiking trails in . . ." They have some pretty great recommendations.
For example, Red River Gorge in Kentucky offers super reasonable passes like 60 bucks if memory serves for the entire summer that lets you park and camp anywhere in the park for as long as you like. There's no picnic benches or RV hookups but it is cheap. Is that what you are looking for?
I will check it out, thanks! My problem is I work in the city so I don't want to be out too far or I'll spend all my time & money commuting. But I will definitely check the books out.
Good Morning @Ssmallchange, In addition to Walmart, and truck stops, a lot of Cracker Barrel restaurants also allow free overnight camping/parking. Sometimes they request you park behind the restaurant - Various satellite mapping resources make scoping out a parking lot super easy! - and as always please be courteous and respectful of customers.
You may want to touch base with the restaurant employees to let them know you are there. Have fun!
I know of a very cool campground in Trade,TN just outside of Boone, NC (about 15 min) about hour 1/2 N of Asheville that has primitive sites on like 80 acres. They have full hook up sites, but also private van/drive in sites and cool tipis and tents scattered around the mountain, very private, also often have garage bays in a barn that you can pull into about 500. yards of Hwy 421, but very quiet and safe. Cheap, think the sites are like $20. just can't tie a dog and leave it, they are picky about that, but this is super close to Boone, close to Skiing, Mountains to Sea Trail, Damascus and the Appalachian Trail. They also offer long term parking for through hikers there as well. But you have to get a shuttle from there to the trailhead, they will take you but only in the back of a pickup truck since COVID, think it's $40 for their shuttle. http://www.tradetn.com the number on their sign was 423. 43 six, 4900