Looks like it's a brass trigger-guard from a Colonial-era-to-early-1800s Flintlock pistol or musket. I cannot be any more specific than that, because Flintlocks are from before my primary area of historical firearms study... but the What-Is-It forum has some ID-helpers who are knowledgeable in the time period of your trigger-guard. They'll probably be along to answer your post shortly. Welcome to TreasureNet. Since you're a new member, here's a well-intended suggestion: It helps to say "maybe trigger-guard?" in your post's title, to attract the attention of the Gunparts experts.