Almost anything, from abacuses to zithers, even cars, and boats. There are a few common sense things that can’t be stored: pesticides, fertilizers, hazardous substances, burnable fuels, explosives, living things, things that give off odors or which can decay, contraband, and food that’s not sealed in cans. Be sure to tell the storage manager the kinds of things you plan to store. They’ll be glad to help you sort it out.