Sugi, in the yard, unless they are associated with a tree with which they have a symbiotic relationship, mushrooms tend to show up where there is an adequate supply of food. This can be dung (including doggie doo doo), rotted stumps, or lots of compost, and in particular, when it has been very damp or rainy for several days. The food source might not be obvious: they usually indicate that decay is happening underground. That's a good thing, as the decay of organic matter (leaves, twigs, tree stumps) puts nutrients back into the soil. Where we have bark mulch and then had leaf and twig mulch decaying into compost in a shady area of the garden is where we saw them develop a few years ago. Aside from that, we rarely see mushrooms in our yard and if we do, it's usually only in our compost area after a particularly damp, rainy spate of weather. Our compost area is outside of the main garden area. Then again, we don't have any grass and very little mulch; we turned the entire yard (1/2 acre) into a garden and we mulch our garden beds with compost, not mulch. We only use mulch over a wide path (a driveway, actually), that extends along the side of our property from front to the back garden and that is pretty much the only place where we see them in the yard. I originally thought this might be a mushroom of the Lactarius family and it physically resembles them, but the fact that it did't ooze any liquid puts that ID in question. I notice that this is growing in mulch. In our yard, the main place where we saw mushrooms was in the one area (a driveway) that we mulched. We had put down a very thick layer of mulch and then Mother Nature did the rest. Mushrooms in grass show up when you have a lot of thatch decaying. In both locations, however, conditions have to be perfect, a mix of the correct temperature, moisture (we saw them develop during a particularly wet spring) in an area where they would have ample food. it's likely the spores have been in the mulch and your soil all along - they are ubiquitous - and the climate allowed them to develop. The structure above the soil is only a small part of the structure; there is likely an extensive underground network which is why they are springing up elsewhere. My own experience in our most recent garden is that we rarely see them sprout, they only sprout when the weather conditions are "perfect" for them, and they have been known to skip years that were particularly dry or where we didn't water as extensively. Over the years, however, in the other places I've lived - always in New England until now - that has been similarly my experience... mulch or leaf litter or compost, heavily thatched lawn, a tree stump, rain, the right temperature... we saw them occasionally, but they were rarely a serious problem aside from the fact that not knowing much about them, we removed the visible structures to protect our pets. We always picked the mushrooms as we didn't want our curious dogs to eat any. You can read about our experience - limited as it was - on our blog. It includes some information about the underground network that develops. The link I've included is to a post I wrote about faerie rings and in particular, one that developed in bark mulch in our yard in 2011. (This is a personal blog abut our garden; we don't have a garden-related business.) I believe we had a few mushrooms surface in that same area in 2012, none in 2013 or this year. In that area, the mulch was fairly old and decaying but we thought we would let it be for one more year. We had put a very thick layer (4-5 inches) on a base of clay. We had piled some twigs and leaves and left during spring clean-up and left them when the weather turned rainy. The following year (2012) we added a very thin layer of bark mulch, and this spring (2014) we added a substantial covering of bark mulch as the existing mulch had decomposed dramatically. My guess is that if you disrupt the mulch and perhaps de-thatch your lawn, you may possibly disrupt the cycle enough to eliminate much of the problem. On the other hand, even if you do nothing, since weather plays a pivotal role, you may or may not see any of them sprout next year. Here is a link that might be useful: Faerie Rings

I've had some of these (on a half-dead box elder) for several years now. The first appeared when we cut off a branch that had been broken in a storm. (Why is it the live branches get damaged, not the dead ones?) Now the mushrooms are forming in other spots on the tree. Just about the whole center of this tree is dead. Someone told me they are shelf mushrooms.

Here's the fern-like volunteer, as described above.

It just needs to be made known that having random strangers ID something from a photo does not always equate to a 100% ID ==>>> exactly my point ...note the article says.. hunt and take to professionals for eyeballs on ID ... i meant IDing on the WWW .... i enjoy the posts.. often seeing things from my yard ... and its fun and informative ... but we have this new age slew of peeps who insist on putting everything in their mouths ... crikey .. go buy a pacifier.. and leave the shrooms alone ... i guess on some level.. i dont get asking total strangers to make sure for you.. whats that all abut.. may as well jsut walk down the street and ask random peeps ... and dont even get me started on the hippie that gave it to the baby.. ken