Beautiful and healthy mushrooms were all over our neighbors' yard last month. They were concentrated on the mulched areas of their garden. This leads me to believe that spores were carried with the mulch. For the gardener, mushrooms are not considered pest, they only grow when the soil is moist. When the season change and the rainfall is less or down to nothing, mushrooms will not grow. Having said so, some gardeners still find mushrooms on their lawns even in the spring or summer. The reason for this has something to do with management practices and it is avoidable. When an area in the yard is over-watered at a frequent interval, the soil remains moist providing a favorable growing media for mushrooms. To solve the problem, irrigate deeply at lesser intervals. It is alright to allow the soil to get close to dry before the next watering schedule.
If you have small curious children in the home, teach them that some types of mushrooms are poisonous. As a kid growing up in the Philippines, I played with all sorts of mushrooms (different shapes and colors) in the wild. Since we never ate mushrooms raw, it was not inviting for a little girls to taste them. There was one rule that my grandmother told me which I still remember and apply even up to this time: Avoid all mushrooms with rings on their stem; they are poisonous. However, this is not the only indicator that a mushroom is toxic or not. MykoWeb provides an expansive reference about the different mushrooms in California.