I'm afraid to fly, so at the end of a successful flight a few years ago, the pilot brought me out those little "wing pins" that they sometimes give to kids. I'm 26, but I think he was trying to be nice & funny.
Anyways, he had to remove the pin part & just give me the plastic wings because he said pins were no longer allowed on planes anymore
Based on that, I'd be afraid of taking pins onboard and would just pack them in your suitcase. While it seems most people haven't had any trouble, you don't want to be that one person that can't bring their pins onboard and loses them.