Nice find! It is called a Die Clash. These are well known ones and happened on a variety of years. They are commonly referred to as a "Prison" Cent as Lincoln is behind bars. Some info on Die Clashes. http://www.error-ref.com/die_clash/
Nice find, especially on a well circulated coin. I would go to maddieclashes.com to look that one up. Being it was a significant die clash, it probably has an attribution to it. You'll be able to identify this coin by that attribution number.
The Memorial is not coming through. It's a die clash. A very nice find especially since the coin has been in circulation for that many years. A true Mint error but common so not a lot of value.