We have a lot of wheels promoting pre-packaged bread. I wonder how they were distributed? As you may have noticed, I'm not one to do much in the way of research myself, so I'm relying on Jessica Helfand's excellent book on the volvelle: Reinventing the Wheel. (Perfect title, isn't it?)
"Tiny enough to to be packaged between the cellophane and the loaves themselves, these 'collect-em-all' almanac-discs combined pictures with propaganda . . . in the context of national pride."
This Wonder Bread guide to U.S. warships is about 4 by 5 inches and is in pretty good shape. The little tabs are worn, though, so I don't like to mess with them.