They make at least a few different kinds of ground anchors that work places there aren't any trees. I remember one that looked like a shovel. And I read that a certain kind of boat anchor works. Once I was too far from the trees and winched myself out by putting my rope around a bunch of bushes. Each bush was so skinny you could break it by hand but together the bunch was strong enough.

 

Another trick is to dig a hole, plant a log or something like it in the hole, tie a rope around it and re-bury it, as an anchor for the winch cable.

 

looking for an anchor myself, most places i get stuck there's plenty of trees but i have 1 swampy area that has pretty much nothing and have to resort to using another ATV but that doesn't work so well if you're alone lol

that said unless you're some sort of body builder good luck lifting it out. my KingQuad 500 is heavy enough on flat ground not even worth trying with mud sucking it down adding that much more weight. it takes 2 people just to lift my Honda 350 if it's in mud and that thing is pretty light