They aren't branches, I can tell you that. Our carport is full of rounds we pull from DNR sites. My brother in law has always heated his home with a wood stove from DNR wood. DNR permits, yes you are taking the wood that is left, not cutting it down.

As far as public lands to cut your own, actual trees, follow the other suggestion for potential on federal lands.

I am not sure, but I don't believe you can actually cut trees down on public land.