I recently heard a theory that parts of Tolkien's legendarium and the Lord of the Rings story may have been inspired by the real-life Ring of Silvianus:
As Wheeler consulted with J. R. R. Tolkien on the name of the god invoked in the curse, the ring and curse may have inspired the One Ring in The Hobbit and The Lord of the Rings. [...] It is hypothesised that Wheeler, in his discussion with Tolkien on the name Nodens on the curse tablet, would also have discussed the ring at The Vyne, with which he was familiar. It is thought that other aspects of the archaeology of the Lydney area, including an Iron Age fort known as Dwarf's Hill, may have influenced Tolkien's writings.
The only sources cited by Wikipedia for these claims are articles in a few UK newspapers (the Daily Express, the Guardian, and the Independent). None of these are particularly reliable sources. But the fact that the Tolkien Society takes it seriously enough to help set up a Tolkien-themed "Ring Room" at Vyne is interesting, and lends the theory more weight.
What evidence is there for the idea that Tolkien based his One Ring on the Ring of Silvianus?
As far as I knew, Tolkien took most of his ideas from Germanic mythology, so a real-life inspiration like this is interesting. Evidence could come either from the text itself or from any kind of extratextual material - other writings set in Middle-Earth, Tolkien's letters or notes, ... Even a reference to an academic paper about this, rather than just newspaper articles, would be appreciated.