For those have read The Adventures of Tom

[Inziladun]

Originally Posted by The Squatter of Amon Rûdh

Of course, just the few lines quoted above will identify this poem to most people as the one Sam recites in The Flight to the Ford. The name of the protagonist is coincidental, having been a very common personal name for centuries.

Indeed. "Tom" is a nickname for "Tolman" in the Shire, and it would seem that "Tom" was common enough in Shire usage for it to be the name given by the local hobbits to the odd person living on their eastern border.
Whence "Bomdadil", though?