I discovered this today at my local farmers market.
It's White Cloud Mushroom. It looks too beautiful to eat however it has a delcioius fresh and delicate flavour. I'm planning to eat some of it raw in salads and some of it fried in tempura batter.
The mushroom man had lots of info about these unusual fungi especially the nutritional properties, however searching on the internet for "White Cloud Mushroom" just brings up lots of references to nuclear war.