Many sites have rocks EVERYWHERE! In older times the poor farmer would have his kids pick the rocks from the field and he'd build a 'fence' with them. After few years of picking rocks from the field the kids figured they needed to go to college in another state and the farmer had a really nice wall/fence. In some areas you can buy rip/rap that they use to stablize creek banks for reasonable prices. A truck and trailer load of bolders can cost as little as eight or ten dollars a ton, delivered. But, having twenty tons of 3 foot bolders delivered onto a new paver drive way can cause some problems with uneven driveway. How do you you move a 400 lb. rock?
Almost as bad is the pile of 3-6 inch round river cobble, it's great for making edging and cobble 'paths', but a pain in making walls, near impossible for making fences. If they deliver the small rock, then we use plan B. Plan B is to pour footings, a six inch deep by 18 inch wide strip of contrete with wire or rebar in it with bits of wire sticking out to attach the rock to.
Frame a six inch wide moveable frame of plywood in two sections eight foot long. It doesn't have to be prefect for a low wall, it does have to be perfect for a fence.
Anyone can build a one or maybe even two foot rock wall. A six foot rock 'fence' is an entirely different matter. First quarter calculus is easier. (Second quarter wasn't.) A one or two foot rock wall with a four foot wooden 'fence' on it is wonderful. Dogs can't dig under it, the wood doesn't rot, and you end up with a great setting bench.