CM's don't just have pins on their lanyards, we saw lots of CM's wearing light blue things from their fanny packs and they had pins on them that we traded with. Also, don't forget that you can go into the guest relations office when you first walk into the parks and they have BINDERS full of pins that you can look through and trade. We also got the big buttons taht said 1st trip or something like that, they also had a nice button at Epcot that had Mickey's face on it and a bunch of different flags around the edges, they probably have Happy Birthday buttons there too.
You can trade with any CM at the turnstiles, rides, with characters, and even the "cleaning ladies" as my DD says!