So, a long time ago, probably high school bio, i learned about some special mushrooms and what they can do to your brain. jk! i learned about their root structure. its SO COOOOL. I learned somewhere that the part of these mushrooms you see are actually the 'fruit', and the entire plant mostly exists underground. Their root systems are CIRCULAR! Ever since I learned this I've been on the lookout for an entire ring or mushrooms, but I have never seen one.
soo.. i googled this just now, and figured out they are called "fairy rings" because people used to think they were put there by fairies. but, actually, it is a fungus that has eaten up all of the nutrients in one area of soil, so it expands outward. the mushrooms that you see on top of the soil are on the edge of the ring i guess? interesttingg....