could be a bigger item that is actually deep. I had something like this a while back and every time I swept the coil over the hole I got a great dime signal. would dig and sweep the hole again and it would still be there. Eventually it turned out to be some big pieces of tin that were a foot or more down. I realize I am posting a few says after your original post but if you have not dug this item up then go back there and swing the coil over the hole to get the signal then keep lifting the coil up off the ground and see where you stop getting the signal. If you are a foot or so off the ground and still getting a signal then it is a big item. Most times this can work with crushed cans also cause they ring as dime/penny range and if you lift the coil off the ground a foot and swing and still get the signal, then it is most likely not a coin.
You still will want to know what this item is so to ease your mind dig away and let us know what it was.
Funkman