The Green-Spored Lepiota
The Green-Spored Lepiota is a common mushroom found in yards and fields across the United States. It's appearance can be deceiving, looking very similar to a common store bought mushroom during certain parts of its life cycle. However, it is poisonous, and is considered one of the most common causes of mushroom poisoning in the United States. It is safe to handle, but one should avoid eating and wash your hands after handling them.
One interesting fact is that they can often be found in fairy rings. In older times, it was believed that they were placed in large circular rings by fairies dancing in the night. Scientists now know that this is a common feature due to the nature of fungus growth. At some point, they started in the center and grew outward in a circular. As the older ones die off, it gives the impression that the remaining mushrooms grew in a ring.