I have personally been to all of these campsites and recommend all of them. They are on freecampsites.net if you want more details.
Smith River Recreation Area, CA
2. Alabama Hills, CA
3. The LOWs, Slab City, CA
4. BLM land outside the south entrance of Joshua Tree National Park, CA
5. BLM land outside of Valley of Fire State Park, NV
6. Bayside Campground, Grassy Point, Pensacola, FL
7. French Farm Lake, Mackinaw City, MI
8. Sage Creek Campground, Badlands National Park, SD
9. Middlebury Library, VT 1 night MAX but the town is adorable!
10. I know this isn’t an actual place but just go to this website. Freecampsites.net You will find some decent spots even if its last minute! I wish I would have used this site when I was in the northeast! It would have helped me so much!