Let me tell you, taking photos for this study must have been a sight. These little mushrooms (which are likely unsafe to eat) spring up in the yard for my corporate job every year. So there I am, on a hot faul day dressed in business-casual attire, trying to discreetly take photos of these tiny wild mushrooms without drawing too much attention. 
These mushrooms tend to appear at the start of fall, right around when kids go back to school. Those days where the sun still feels warm like summer, but the nights are getting colder. A subtle reminder that summer is ending.