That stuff that looks like foam is actually part of the mushroom's root system, and it's perfectly solid--actually, it's probably firmer than the rest of the mushroom. It's normally buried under the damp leaves, but I dug it out to take a look. Root systems are very diverse--I hadn't seen one like this before.
Some fungus I found in some heavily wooded, shady forest. They were surprisingly hard, although they look very soft, they were about as firm as an unripe peach.
This is not a picture of mars...it's actually a close-up of the top of the largest mushroom. ;-)
These are the mushrooms...three lovely specimens from my neighbor's yard. The rest of the photographs are these mushrooms, shot from different angles, with close-ups, etc.
Yes. I'm obsessed.