I lived in KC for years but never hunted there. That said, while working at KSHB-TV, we discovered a privy on the station property. They were installing a new satellite dish and unearthed loads of beautiful bottles.
One of my favorite museums in KC is the one featuring the unearthed Argosy Riverboat, complete with all its contents. Now that was the find of all-time.
Love the tags and if they are railroad items, even more special. If you ever have time you should see if there's a historian at Union Station who might be able to verify.
Cheers!