WW1 United States Army general use cart wheels, the "a green color" is the earlier yellowish-green equivalent of WW11 olive drab. These came often with a short axle stub and a bracket with swing arm clamp that was intended to be bolted to whatever wooden body you were making for the cart. The clamp allowed the axle stub and wheel to be easily removed. Sometime these have pneumatic tires and a few have a steel ring bolted around the outside of the rim with the hard rubber tire vulcanized to the ring.