Looks like an early period umbrella part. Found those where I have found the the brass umbrella sprocket and several brass support ribs/arms. Someone on TN once displayed a complete umbrella skeleton display. Wish I would have archived it on my PC.
TN does a fantastic job providing an avenue of information on finds as well as hosting some very experienced readers and I love it for that. If there was ever room for expansion, I would love to see a section where known items are posted as stickys (such as the Navy Blazer button) to assist with ID. Just saying.