Found this detecting this weekend. I posted this on the Civil War and the What Is It forums, and found out it is either a Civil War sword plate, or a pre-Civil War Breast Plate.
Thanks. Here are some buttons I dug at the same site. One says "Big 3 Cincinnati," one says "AJ Town Co. Boston," which I found were made between the 1870s and around 1946. I have no idea on the other. I cant figure out what the BIG 3 Cincinnati button is. I seen online that there was one for sale on ebay, and they thought it was sports related, but didnt have anything to back that up. So dont know.
Thanks everyone, I'm very happy with it. Shen I found it I was covered in dirt and I thought it might be another jar lid then I wiped away the dirt and realized how heavy it wa. I then seen the eagle and started getting excited. I hollered at my buddy and hvsaid that he had seen one on a show andvtha twas Civi War. I thought it was too good to be true until I looked iy p and then everyone on here confirmed it for me.