DivePhilippines
You can tell it is a decoration because it returns experience. Food items return energy when used. Decorations return experience when you buy and place them. I don't think there are any non-decoration shop items that return experience.
Almost always, the special item from an event can be used to get food (in the shop, in the kitchen or both) and to buy a decoration in the shop for experience. This provides a way to use up any left over after buying equipment. If you don't do either, the trader may show up eventually to buy them for coins (but you also get coins when you sell the decoration - I haven't compared the amounts for one vs the other).
