Joel, by itself I doubt if the serpent sideplate has much value as a broken/discarded gun part. But the history is intrigueing. I always start by asking...WHO....WHAT...WHEN...WHERE and WHY?
We know what it was and where it was found, but the rest....?
We know trade guns were very common in the upper Great Lakes back when.
Was it ever actually on a trade gun or in a box of spare parts? Where is the rest of the gun? Keep digging! It wouldn't have been removed just cause the tail was missing would it? Maybe it's a part off a junked, lost & found gun, that was carried around as a trinket or ornament. Neat trade trinket, huh!
It's is so well preserved, I wonder if it isn't from one of Curly Gostomskis old (20th century) kits. May not be old at all.
Many builders threw junk & trash around a foundation of a building before backfilling. Maybe that is what happened here.
I once found a full box of Prohibition era whiskey bottles (empty, dangit) and other bottles jars, broken dishes and a copper Model T hubcap around the footings of a garage I was excavating.
Fun to wonder about!