I remember back during the days of Pokemon cards, my younger brother had made a trade with a close friend and received a Machoke (just a small trade, nothing special), but afterwards realized that the Machoke was a first edition. My brother's friend wanted a trade-back, but my brother declined. Weeks later the card disappeared; mind you, this wasn't a "big" deal card. A large number of the cards we had at the time were first editions, as this was near the beginning of the craze.
Fast-forward maybe a full year later, and my brother comes home from his friends house one day waving the Machoke in the air. He told me he saw it in his collection and took it.