So when I was a kid I lived in the countryside in Ireland. There is a lot of folklore and myths, but the one thing I remember most is, uh, coming across a number of fairy rings in our fields–which is, um, basically a circle of mushrooms or a circle of different color or height grass. I was always told not to walk into these circles, because they are magic fairy forts–which I believed–and that if I disturbed them the faeries would come after me and cause mischief, like putting thorns in my bed, um, or misplacing things on me. Also we were told if we do step into it, to be careful not to take anything from it, or break anything because then the same thing would happen–they would come to get that stick, or, uh, whatever we took, back.
Legends about fairies and elves are very important in Ireland. “Believing” in the fair folk, whether you actually believe or not, is considered patriotic. Children raised in Ireland are expected to know of and participate in the belief of the fair folk, although, as is the case with my friend, they largely grew out of the belief of these legends as they grew older.