Fairy rings are the way that spores or something work with mushrooms. It's not magical.

[Forever the skeptic, he wasn't about to profess to believing in things that were explained by science. No matter what world you came from. Mushrooms were mushrooms, and there were no small creatures out to get you.

Those were all very real, and mostly human-sized, in his world.]

Yeah, me and Jack met in England so you could say I've heard the stories before, though. Cute for telling the kids-- at the place where we live.