Richard Mason found a clay jug while renovating a house on Lindisfarne Island, Northumberland, in 2003.
But it wasn't until 2011 that he realized the jug contained 17 rare coins.
An investigation declared the treasure trove a treasure, and the Newcastle Antiquarian Society wants to raise about £31,000 to keep it in the area.
Ten gold and seven silver coins date back to the reigns of six English sovereigns and several European states, one of which, a gold scudo of Pope Clement VII, who refused to annul Henry VIII's marriage to Catherine of Aragon in the 1520s, is thought to be worth only about £30,000.
The oldest coin is a silver grit of King Henry VI, minted in the late 1420s or early 1430s, and the most recent is a silver sixpence of Queen Elizabeth I, minted in London in 1562.
"Mason's Treasure" is on display at the Hancock Museum (Great-North Museum) in Newcastle-upon-Tyne, England.