Garden Mushroom Identification
Looks like shaggy ink cap, Coprinus comatus, to me.

Blacksmith37's answer suggests that shaggy mane is the usual common name. I hadn't heard that name until I looked at the Wikipedia page. In the U.K. it is shaggy ink cap, inkytop, inkhorn or lawyer's wig.

Update

This is a good general source of information. Also comatus (Latin) means hairy.