I found these two objects in holes about 5 feet from each other. I saw the distinctive curve of horseshoes. Other they didn't read up as iron, nor do they look iron. Are they horseshoes made of a different material, or something different entirely.
+1 Poured lead seal for older possibly sewer line. back when they still used lead pipe for water lines, all the way into the early 50's it was SOP to seal pipe joints with lead...