This appeared in the goat pen the other day:
As you can see, the patch is longer than the 12" ruler, and the largest is about 6" across.
I have no idea what kind they are; I haven't gotten to the point of trying to identify fungi yet. If you know, please tell me.
We kept an eye on them for a few days; eventually one of the puppies laid down on them and wiggled around, effectively destroying them.