At the time of the civil war, what we now called "canned goods" (vegetables, fruit, etc) were made by soldering tin-plated sheetiron together to form a cylinder, with a solid sheetiron disc on one end, and a washer-shaped disc as the top lid. The can was sealed by soldering a smaller sheetiron disc onto the can's open-at-the-center top lid. See the photo below. That SEEMS to be what we see in your photo... due to the rust-encrustation, it's difficult for me to feel very certain. However, that method continued in use for more than just a few years after the end of the civil war. There's no way to know whether your can parts are from the war years or sometime later.