Obviously not a US large cent , im certain it should actually be that shape , i cant place it offhand but ive seen that coin before , the style i mean.
Yes,I am pretty sure it is a large cent. Same size and thickness. Hard to tell from the picture but can make out part of the writing on the back along with the coronet head on the front. Over 200 other US coins dating between 1850 and 1875 have also come out of this site along with a 1826 shiny yellow one. Many of the coins have square nail holes or have been altered some way or counter-stamped. There have been some civil war and other tokens recovered as well. Maybe someone was just bored one day or was trying to make a good luck charm or love token.