Don't listen to the fae. Don't eat the mushrooms

Depends on your location, I think. There were different rules in different areas. I remember being told that if you were to walk round the fairy ring clockwise enough times, you would gradually be able to see through the portal into the fairy world. If you went the other way round, something bad happened.

Of course we didn't believe it one bit, so ran around it the way you weren't meant to.

Initially we thought nothing bad happened - but then suddenly, 30 years later, bam! Brexit.

They're even cooler when you find them in the forest. You don't realize what's happening at first, the ground is uneven, the forest obscures it. But then you realize you're in a perfect circle of magical fungus. Goosebumps