I use "plastic novelty items" as the description on my customs forms. This was suggested by the friendly clerk at my post office. I occasionally receive items from outside the country marked "poker chips" and that works too. Unless you plan to buy USPS insurance or send the package Registered, there's no reason to value the shipment over $5-10 on the customs form. That range doesn't seem to ring any alarms with customs. I don't check either 'merchandise' or 'gift' on the form and no one has ever complained.