Pick yourself up some wood pallets and landscape ties. Place the ties so they are the same width as the pallets put a hole in each end and drive a piece of Rebar through the tie and into the ground and then just lay the pallets on top and your good to go.
We picked up 4 pallets and 4 T-posts [farmers use these a lot to string barbed wire.]
We laid 2 of the pallets side by side and put the T-posts into the ground at each outside corner. Then we dropped one pallet on its end over the T on one end and the other pallet on its end over the T post on the other end.
Basically you have a great big |_| keeping the firewood off the ground and keep it corralled between the two upright pallets. Total cost about $10.