From Fox News:

Found in a field near a historic Roman town in southern England in 1785, the gold ring is inscribed in Latin, “Senicianus live well in God,” and inset with an image of the goddess Venus. It is larger than average, weights 12 grams, and is believed to date from the 4th century.

The ring is believed to be linked to a curse tablet found separately at the site of a Roman temple dedicated to a god named Nodens in Gloucestershire, western England. The tablet says a man called Silvianus had lost a ring, and it asks Nodens to place a curse of ill health on Senicianus until he returned it to the temple.

An archaeologist who looked into the connection between the ring and the curse tablet asked Tolkien, who was an Anglo-Saxon professor at Oxford University, to work on the etymology of the name Nodens in 1929.

Other rings of power rumored to have served as literary inspiration:

The Ring of Gyges

A thought-experiment in Plato’s Republic features the myth of a ring of invisibility discovered by a shepherd in service to the ruler of Lydia. The shepherd used the ring to accomplish evil deeds. Glaucon and Socrates debate over the inherent nature of man by imagining if ostensibly “just” and “unjust” people would both behave corruptly if they had a ring of invisibility that could protect them from the consequences of their deeds.

The Signet Ring of King Solomon

Apocryphal legend has it that God gave King Solomon a ring that granted him authority over demons for the purpose of supernaturally constructing the magnificent Temple.