It's be easy if you wanted something simple. Set some 4x4's in the ground and just nail the pallet boards up longways on all four sides. To get more complex you could elevate it a little like DocD did up there, and enclose the sides with the boards, then cover it with a simple roof and put some tin on top. I've actually got a bunch of old fence panels laying by our cabin at our land, wanted to make ground blinds at field edges for turkeys, just haven't gotten around to it. This shouldn't be too tough though, just mess around with it til you hit on something.
Nice blind up there Doc, I like it