The Black Death is identical to the plague that hit London years later—the plague continued on and off for hundreds of years. I’m sorry, but Wikipedia is good for spot checking and for a quick reference, but it is hardly a good authoritative reference on anything—fact-checking things is an important part of my day job, so I know. As for Snopes—you’ve got to be kidding
I don't believe that you have fact-checked your position on the "Ring Around the Rosie" rhyme.
I used to believe the same thing about that rhyme, but I was open-minded enough to change my mind when I saw that there were much better arguments against the usual theory.
If you are looking for an "authoritative reference", Peter and Iona Opie were acknowledged for decades as the greatest experts on English children's rhymes. (Their work is referenced by both the Wikipedia and snopes articles.) They did not believe that this rhyme had anything to do with either medieval or more recent plagues. (You can read a quotation from one of their books on this page.)