Which fungus?

I was on my way back to the car after an enjoyable afternoon at Minsmere yesterday when I saw this:

I can see that it's definitely not a parasol or a puffball ........ beyond that, I'm clueless!  If someone would please enlighten me it would be most appreciated.

Our herring gulls are red listed birds.  Think about that the next time you hear some flaming idiot calling for a cull of them.