These are beautiful coins. For all but a few dates, and for coins in worn condition, they are worth a few US dollars. In well preserved condition, like the one shown in the picture, the value goes up to $20 or a little more. Approximate catalog values are:
worn: $3 US dollars approximate catalog value
average circulated: $8
well preserved: $30
fully uncirculated: $150
Use our Important Terminology page to convert these inflated catalog values to actual buy and sell values.
Like all but a few special dates, mtollin's 1917 is a common date for Newfoundland Large Cents. Values go up slightly with age. 1865 is a little more valuable than 1936. If you have a coin dated 1885 or 1888, multiply the above values by 5. 1913 and 1929 are extra-common dates, so they are worth less than the values shown above.
Some coins dated 1880 are super rare. They are known as the '1880 oval 0' variety. Most Newfoundland large cents dated 1880 have the date written out as '188O', with a large circular zero. But a few coins have the date written out as '1880', with a modern oval zero. The coins with an oval zero catalog at $500 when average circulated, $2000 when fully uncirculated. So if you have the 1880 date, check that zero!
Like most British coins, the reigning monarch is shown on the front of the coin. So your coin may have a different king or queen.