Three Sparrows and a Mushroom

I can easily identify the sparrows, Chipping Sparrow, White Throated Sparrow and a female House Sparrow, but the mushroom is another thing.  It is quite large, about 4 inches, and it is all by itself in the lawn.  Since taking the photo it has "opened up", like an umbrella.  I haven't been able to find anything like it.  Odd.  A rainy Cinco de Mayo Sunday.