Such a coin does not exist. In the event that somebody did produce a gold Halfpenny, it would be worth whatever the current bullion value of gold is.
28.925 million British 1939 Halfpennies were minted.
Farthings were made from bronze. If you have a silver Farthing, somebody has plated it and it is subsequently of no value as a collectible.
Such a coin does not exist. Canada has not used the British sterling currency system since the mid-19th century, and has never issued a Halfpenny or half cent coin since Confederation. If the coin has no country name on it and has a sailing ship on the reverse, it would be a British Halfpenny. Alternatively, you may have a privately minted Halfpenny token.
The value of a 1939 George VI British silver half crown can vary depending on its condition and wear, but ranges between $3 and $20.
British Halfpenny coins minted from 1939 to 1945 uncirculated and in absolute mint condition might get anything from £6 to £20 GBP depending on the year. If they have been circulated, not much.
There was no British 1939 Crown coin minted.
A 1944 Halfpenny with a sailing ship on the reverse is a British Halfpenny.All British Halfpennies from 1937 to 1967 featured Sir Francis Drakes "Golden Hind" on the reverse.All Australian Halfpennies from 1939 to 1964 featured a kangaroo on the reverse.See the link below.
About $6, mostly for its silver content
The US mint never made pure silver dimes. See the related link below for more information on the value of 1939 US dimes.
Check that coin again. There were no US silver dollars minted that year.