That's called a lamination flaw. According to my RedBook's errors section, a zinc cent with a major lamination error, such as yours seems to be, can be worth $10-$15, but if you were to look at similar items on Ebay, I doubt that you would find them for nearly as much. Lamination flaws occur when some kind of foreign substance like gasses or dirt gets trapped inderneath the copper coating, which then can burst out and tear that coating when the pennies are rolled out to their proper thickness. Good catch! ~AJ
This is most likely a copper-alloy cent, not a copper-plated zinc cent. Lamination errors are very common on solid alloy cents. They are quite rare on copper-plated zinc cents. Plating does not ordinarily peel up. It may blister and the blisters may "pop", but it doesn't separate in sheets, except on very rare occasions.
