Someone made a magician's coin from a Kennedy Half Dollar and a British Penny. Value is a couple dollars as a novelty item. It's the goddess Britannia, not a "Roman guy" and that's a trident, not a fork!
I think you mean a 50 cent coin. The mint marks for a 1916 are on the front of thecoin and value is very wide depending on grade an mint mark. The list is from $45.00 to $1200.00. Take it to a qualified professional.
There 186,000 of these sterling silver Cayman Islands $25 coins minted that one year to commemorate the 25th anniversary of Queen Elizabeth II (1952-) and Prince Philip. It contains 1.5271 of an ounce of silver and thecoin by itself may be worth about $30 depending on the price of silver, amount of wear and collector demand.