What are your best moments of finding something in the wild that you unsuspectingly found out was rare, later on? Or, perhaps, what are some items you bought new back in the day that you later found out were rare and valuable?

Mine was a few Saturn games I found back in 2008. Bought a dozen or so for $3.33 each, and three of them ended up being worth over $50, and some being worth around $30.