My grandfather introduced me to numismatics (coin collecting )when I was just a kid. We'd dig through bag after bag of unsearched coins looking for a rare find — like a minting error or a coin that could complete some series he'd been working on.

My granddad was always on the lookout for the Million Dollar Nickel. We'd have piles of nickels spread out on his card table and he'd tell me the story of The Liberty Head Nickel (even though I'd heard it a thousand times). The nickel was first issued in 1883, without the text to indicate its five-cent denomination. It didn't take long for some unscrupulous folks to cash in on the mistake.

The most famous was a deaf-mute named Josh Tatum, who allegedly gold-plated the nickels and passed them off as five dollar coins. The popular story is that Tatum wasn't convicted for his crime because no one could testify that he had said anything fraudulent.

But the story doesn't end there. In 1912, the mint was ordered not to produce the nickels in 1913--they were supposed to wait for the new Buffalo nickel design. So how and why did five or six 1913 nickels get into circulation? Nobody really knows, but the last one to surface in 2013 sold for over $3 million! The buyer said he would have paid $4 million. I don't know about you, but I'll be looking closely at every nickel I see from now on!