I know that the metal detector is not finish but i know what there are some items that will be found using the metal detector like tin can, quarter, and gold. Maybe it will be more fun if you can find more items. Note: I do use a metal detector as a hobby and i do understand what you can find.
List of Items:Nails,Rings,Watches,treasure chest with random amount of unites and or gems, gum wrapper, random chunks of iron, bullet shells, bottle caps.
Also it will be nice to have a coin date system. An example will be a newer quarter will worth 25 units but a much older one can be worth double. For example a 2005 quarter will worth 25 units and a 1924 quarter will worth 50 units and if its more older, it should increase the price.