I went back to the site we have pounded and got a popping mid-tone with an iron tone! moved the leafs and scrubed the ground THAN the signal came in sweet mid-tone deep. Out popped a British copper well worn. Also got a harmonica reed, melted lead and another button. The front looks like it's made of iron and the back looks like brass???? sounded like the copper did (mid-tone pop with an iron sound??)Also found what looks like a carriage spring??