Alan Smith, who was working in a Lincolnshire field, detected the treasure in a burial mound, which is believed to have belonged to elite Anglo-Saxons.
Fighting took place in, and around the town and, at one point, Bolles was forced to take refuge under the Ramsgate bridge.
Human remains, found during archaeological visits to Louth Park Abbey during the 1800s, in 'a little space surrounded by a ditch', were believed to date from the Civil War as two cannonballs, from that era, were found with the bodies.
The finds are now being processed under the Treasure Act and a report is being prepared for the coroner, who will decide who will own it.
Senior lecturer at the University Of Sheffield, Dr Hugh Willmott, who has excavated the Louth site, said: "The finds are intriguing.
To the east, the water was sent into two fishponds, one 'of great size', was still full of water, and stocked with fish, in the late 1800s.
A plan drawn up in 1873 from historic records and site visits suggests that at its most developed the abbey included a church, sacristy, chapter house, store rooms, monk's parlour, Abbot's lodge, kitchen, monk's refectory, Lay brother's refectory, undercroft with dormitory above, guest house, cloister court and lavatory as one complex, with a separate infirmary building and gate house.
In March, an Anglo-Saxon island was found and in August, new evidence was uncovered to prove the town's claim that it was the location of Sidnacester Cathedral.
Archaeologists revealed that an 'ordinary-looking field' in Lincolnshire was actually once a settlement with trading links across Europe.
It developed where the ancient trackway along the Wolds, known as the Barton Street, crossed the River Lud.