Features for loading, transporting and unloading of items are disclosed. Systems, devices and methods for such operations using a tray are described. In some embodiments, a tray having a moveable bottom allows for switching between a configuration for loading and unloading items in and out of the tray and a configuration for transportation of items inside the tray. The trays may also be stacked, for transportation of multiple trays at once, and nested, for saving space when storing the trays. In some embodiments, the trays may be used in conjunction with loading and unloading systems.