What is a good subject for a calendar representing all the months of the year?

For art class, I need to come up with an original ideas for a calendar. I can use any media. I need to represent each month with an object that makes sense and all falls under the same category. For example, someone did underwear for each month. For march they did four leaf clovers, hearts for February, and school supplies for august. Another example is drinks: Capri sun for august, eggnog for December, and Champagne for January. I need an idea like these. HELP!