On my computer's monitor, your photos appear as being "stretched"... so I cannot accurately judge your sheet-iron oval-shaped object's proportions or dimensions. Cartridge box oval plates were made of brass, stamped-sheetbrass, or copper, or pewter.,, not iron. There was a Confederate-made sheetiron oval-shaped belt buckle, known as an "Iron Oval CS" for its shape and the (large) letter-markings "CS" on it. It had three sheetbrass hooks soldered onto its back, which are usually missing. But based on the size of the cigarette lighter in your photos, even allowing for the photo distortion, your sheetiron oval sems to be too large for any possibility of being an Iron Oval CS buckle (whose size varies from 58MMx87MM to 62MMx89MM).