Boondocking is the term most full timers use when talking about free camping. You are out in the boonies!
The National Forest Service and the Bureau of Land Management offer areas where you can camp for free for 7-14 days. My first boondocking site was on BLM land in Utah. Heavenly.
The NFS has, by law, a map of each district within each NF. On this map it shows every place you can camp for free. Look of dots on either side of the roads. These maps are also available on your phone for free via Avenza. You have fourteen days. I have received conflicting reports on how far away you have to move at the end of 14 days. Some Rangers have said 25 miles, one said out of the district, and one said that I had to move out of that National Forest. I just keep a low profile.
The BLM is a bit looser. Camping on public lands away from developed recreation facilities is called “dispersed camping.” Dispersed camping in BLM is allowed on public lands for no more than a period of 14 days within any period of 28 consecutive days. Then you have to move 25 miles away. There are unmarked spots
One of the best non governmental resources is a website called frreecampsites.
I found my favorite free site because of them.
You can do this!