M.K.: Never heard that one.
torq: I think “tall tale” is your best bet. By definition, myths are of a moral or philisophical nature. Legends deal with less weighty subjects, but both are usually believed as true (although myths usually hold deeper meanings that transcend the story itself). “Folklore” can be myth, legend, or tall tale, and doesn’t really have a precise meaning. Jesus’ parables were fictional, but then Pecos Bill is hardly in this league. I suppose that superheros like Superman and the X-Men could be considered modern-day tall tales.
But the story about the dogwood tree asking God to mutate it is definitely a tall tale.
–It was recently discovered that research causes cancer in rats.