Ooohhh, I get to answer right after Jock Scot!

Unless you're in a 'pipe band, there are no rules about which pin you can/can't wear. You can wear a sword pin, a penanular broach, a stick pin with a clown on it, or whatever else you like. I have a silver dogwood pin, an enameled dogwood pin which is white and green, a brass stand of 'pipes pin, and a "traditional" sword-type pin. If you wear something other than a "traditional" kilt, pin, be ready to talk about it with anyone who asks.