The symptoms are flu-like. In fact, one friend was so confident that Lepiota naucina was a good edible species that it wasn't until the third time that he ate the mushroom and appeared to come down with the flu that he recognized the mushroom connection. There are many perfectly good edible mushrooms that make some people ill but most people eat without any adverse effect. However, there are some mushrooms like this Lepiota naucina that make a disproportionate number of people ill. Also, this mushroom is common in lawns and even choice edible mushrooms should not be collected from golf courses, roadsides, well-kept lawns or other places that may have been sprayed with pesticides or contaminated with heavy metals.
Mushrooms readily concentrate both pesticides and heavy metals and can become toxic as a result.