You got a planter for sure, if it ever had a box on top it may have been for corn, but that square hole looks big enough to plant potatos, was steered by hand, and probably had a single horse pulling it, heckuva neat find, would have had big wooden handles like a walking plow. The other two spindles are the rear axle to that wagon, most likely. I got a theory here, when I was a kid, wagons like those early moving vans were often used for storage sheds out the back door of the repair shops/blacksmith shops. Later on there would be old panel vans on blocks doing the same thing. I am thinking they found this old wood wheeled moving van, parked it behind the shop or barn, and nature and gravity took its toll, or there could have been a fire. The hammer heads could possibly tossed into the van due to broken handles, to be fixed later, later never came. Are there any old photographs from the 30's or earlier taken there on the place?