A granular commodity wagon or grain cart assembly that includes a movable conveyor assembly supported by the grain cart. The conveyor assembly is movable between a stowed position and an in-use position. When in the stowed position, the conveyor assembly facilitates a compact footprint of the grain cart assembly for storage and/or transportation. When in the in-use position, the conveyor assembly can be oriented in generally longitudinal alignment with the longitudinal axis associated with the direction of travel of the grain cart assembly to facilitate loading of the cart with a commodity, such as grain, seeds, or beans collected by a harvester or other secondary harvest or collection and/or transport and/or storage vehicle or container.