This response is strictly a personal response as this is a situation the rules don't cover (and subject to DM interpretation). Expect Table Variation (TM)
I have a druid with an insignia of claws (I wear it on a loose cord around my neck). Cloaks are also a possibility, as are rings. Goggles may also be on the table depending on the size of creature you become.
IMHO, things that are definitely (or usually) off the table are armor, weapons, boots, bracers, brooches, and other similar items. Items that are in a grey area include hats, headbands, belts, rings, and the like. Expect table variation, but under most situations, most DMs will allow it if it even remotely seems like something the animal could use.