Both posters are right. There are "newlywed" pins you can buy, but there are also free pins you get at guest services. These free pins are large round white pins with mickey & minnie dressed in wedding atire.
In january we bought the Hat w/ears and veil w/ ears. The hat rubbed you pretty hard on the forehead, so we switched to buttons later. We recieved just as much attention from the free buttons as we did the hats.