Front Yard - Grass Grows - Other Stuff Too

The addition of recent rainfall in the area and a reduction of heat from the sun, given it's been almost 3 months since the summer solstice, has occasioned my grass to grow a bit over the past week or so.

For the past few years I've noticed that in addition to grass growing in late summer, I also get this small crop of mushroom-looking gizmos. Some are tall and fairly soft, others grow low to the ground and sound almost as hard as rocks after I pop 'em up and go over them with the mulching mower...loud noises definitely emanate from the trusty ol Toro when it works on 'em.

These little rascals seem to be clustered around an area that was occupied until about 5 years ago with two large Pin Oak trees, shown in this image. Ignoring the benefits of having the trees in the front yard, I decided to have them removed and the stumps ground before the BG&E-contracted trimmers came thru and butchered 'em to save the 'wires'.
My neighbors suggested I have my head examined (which I definitely do need) for taking the trees down and told me I would be sorry in the long run. It appears the dirt that I covered the ground stumps with is no impediment to growth of these mushroom-thingies from the stump residue.

The ol' Pin Oaks are indeed striking back at me for my shortsightedness in having them removed. Just one more curse on this 'old fart' for his poor decisions of the past.

Primary election today here in Maryland; get out and vote,
JD

PS - Here's image of neighbor's Pin Oaks following BG&E trimming to prevent potential storm damage to their wires and to insure continued customer service. The result is pretty devastating, isn't it. I understand the BG&E rationale for the trimming, I just don't like the visual results.