In the mid-17th century, the nine most influential pirates of the Seven Seas (later called the Pirate Lords) formed an organization called the Brethren Court. Each of the nine Pirate Lords agreed to keep a piece of eight to present at meetings of the Brethren Council, although the term came to be applied to a variety of objects and trinkets as the pirates at the first meeting were without doubloons and decided to keep the name "pieces of eight" to refer to these objects. During the first council, these nine pieces of eight were used by the Pirate Lords to trap the sea nymph Calypso in her human form, following the instructions of Davy Jones.

When the First Brethren Court was formed, the tokens that indicated membership were originally intended to be actual pieces of eight, also known as Spanish dollars, a real coin in the age of sail that became universally recognized and therefore very valuable. However, since the first Pirate Lords were somewhat lacking in treasure, they chose to use an eclectic selection of other objects, including a playing card, a prosthetic eye, and an ancient Siamese coin. However, they continued to use the term 'Pieces of eight', despite the fact that there were nine members.