My alma mater made these keychains. They are called “disco tray keychains.” For many many years, the cafeteria has used the same vendor for their cafeteria trays. Most of the trays are a solid green similar to the color of the keychain. A small percentage of the trays, however, are this faux marble with the same color green as a background with a gold metalic vein running through them. These trays were called “disco trays” They got mixed up with all of the other trays and it was pure chance as to whether you would get a disco tray when you stepped up to get your food. So, if you got a disco tray, it was a sign that you were going to have a lucky day.