• The coin is scheduled to be up for auction next month in London.
• The silver shilling was made in Boston in 1652 and used by early New England colonists.
• Worth pennies at the time it was made, the single coin is expected to sell for the equivalent of up to $300,000.
• Morton refers to the coin as the "star of the collection."
• An ancestor of an early New England settler discovered the coin in a candy tin at his family's estate in the UK. "I can only assume that the shilling was brought back from America years ago by one of my forebears," he said.

Big Picture: This coin is one of only 40 in existence. Rhode Island coin expert Jim Bailey said, "The coin has tremendous eye appeal ... this specimen can be called the finest known."

Rare coin made in Colonial New England could fetch $300,000