I've got quite a few, but I never wear one.
In my opinion, they do not look like they belong with a nice jacket or suit (or uniform, for that matter), certainly not like a beautiful pocket square, etc...
I reckon lapel pins are pretty big in the states right now. I run a instagram page for and post a variety of lapel pins. They can range from formal to casual as well. Generally I would say a floral lapel pins would be popular at weddings and dinner parties. Where as a gold plated or rhodium lapel pin would be a great accent for a work suits and help you stand out from everyone who wears a suit to work.
You can check out some pics here if you want some ideas :)