In doing online research, I learned that it could take quite awhile for some of the former tree matter to decay causing a delay in the appearance of these "shrooms," which are actually fungal matter.
And, unlike in the human world where fungi is often not a good thing, it's actually beneficial in many parts of the plant world.
Mushrooms grow where there is healthy organic matter in the soil. While they are not necessarily bad for the lawn, most homeowners find them unattractive and remove them down or apply fungicide treatment.
The ones in our front yard provided some good photo opps. These photos were au natural with no post processing or special effects applied.
Shortly after this photo session, I eliminated them from the lawn because our home is "on the market" and these clumps may not seem attractive to a prospective buyer of which they were none recently. And, there is that whole issue of "curb appeal."
For a short time they were great subject matter. You don't need to go far to find photo possibilities, just take a walk in your front (or back) yard