Alright, well here's a belated post.
Ever since I made the cloak-ish looking big cozy sweater cloak last year, I've been browsing the internet for penannular brooches.
So after I finished my velvet-and-wool cloak I decided it was time to finally buy one! I found this lovely little site called Thorthor's Hammer that has a nice section of penannular brooches.
I actually ended up buying two, because the really simple ones were nice and cheap and it occurred to me that they'd work well for fastening a medieval belt as well.
I'm impressed. They're quite nice, and the shipping was inexpensive and quick.