The only matching items in the catalog were the silver coins from the Free imperial city of Aachen. They didn't match entirely, mind you, and since I couldn't find any coins featuring a pine tree, I came to the brilliant conclusion that I must have discovered a new, hitherto unknown 614-year-old silver coin.
After taking a lot of pictures of said coin, I came this close to posting a very enthusiastic-sounding request on the "Coin identifications and valuations" forum. Fortunately, I decided to give google one last try - otherwise, y'all would have ended up with the most hilarious thread in history. After going through some pictures on the google image search, I've found my precious! After following the link to a derelict message board, I realized that my potential retirement fund was, in fact, a novelty 1 penny copper Shire coin from Lord of the Rings. According to some sources, its value is a whopping $4, assuming I manage to find a buyer for it.
What about you? Do you have similar stories about "unicorn" coins that seemed like the find of a lifetime? (I hope it wasn't just me!)