I don't have a clue about coins but I just bought one of these a 1806 Bittannia, it has Edward the third on one side and on the other it has a person with a shield and three prong fork and a ship in the bottom left corner. Any ideas on a valuation ?
I think you're describing an 1806 English Penny - matches the description - but that was George III, not Edward III. It's not silver, but it would have some numi value depending entirely on the condition. Could be worth as little as $20 though.
I will post some pictures when I can and put it up for auction. I've owned it for 20 hrs now so it's time to Move it on.