Errors increase the value of collectibles because a limited number go into circulation before it is spotted and corrected.
Business Intelligence | From W.D. Strategies on MSN

Got a $2,000 Quarter? Here’s What to Check Before Spending It

The Mystery of the Wisconsin Quarter Error What if that ordinary quarter in your pocket could actually be worth thousands of ...
According to Gainesville Coins, the 1914-D Lincoln Wheat cent had a very low mintage in its series for its year. The rarity of this coin makes it worth at least $175 to collectors.