Have seen what they use....metal pipe with a v cut at the end, Plug it in the ground and drop the coin thru the pipe withdraw the pipe and step on the plug. Certainly easier than planting with a digging knife.. Buries the coin several inches deep and if notch in ground is properly stepped on tough to find the notch in the ground. Burying a field with many coins is quite a job and the less bending the better....