A trailer having support wheels and a frame adapted to be hitched to a truck, includes a support track extending longitudinally for supporting an unload conveyor. The conveyor is mounted by a turret to the support track and, thus, to the trailer frame, permitting the turret to move in a fore-to-aft direction, as well as to rotate about the vertical for about 180°, providing flexibility in use as well as transport and storage. A support module, carrying at least one storage container is mounted on the trailer frame. The storage containers may be provided in a number of different sizes and they may be arranged in various configurations suiting the user's needs. The turret is positioned along the track beneath a desired seed container, which may then be unloaded by the conveyor to fill a planter seed box or grain drill, or for other seed handling applications.