peg out a meter square and take off the top soil.
Section it and do each quater one at a time down to a foot deep.
if you need a hand held metal detector no doubt nigel can lend you his.

If you find more than 4 coins call in a local archaeo in case there is a hoard.
any gold torc's you find sell on Eb.... sorry, cover up and call in the local FLO

have fun