NOT shitake. We have two successful mushroom farmers in the area, and they put the spore plugs between the bark and cambrium of oak logs, later plunge into icy water for x# of hours to force the fruiting. You really need to research and follow the exactness to get fruiting sh'rooms.

I tried doing the mushroom thing a few times, never got anything out of it. That's why I look for wild mushrooms instead, much less frustrating!

Those look like some kind of Lepiota, which could be anything from dealy to delicious. But they definitely aren't shiitake. I saw some very similar a day or two ago growing from a stump.