Posted: 31/10/2013 at 20:55
Stacey - Firstly, I'm not an expert - just someone who's been on a couple of Fungi Foray days - It's really hard to tell from a photograph but I think it might just be a Death Cap - the colour's not quite right, too pale - they're usually more of a greenish colour, but if you've had a lot of rain the colour can fade. Also, there is a more unusual white variant.
The base of the stem of the Death Cap usually has the remains of a sort of 'bag' or cowl around it which I can't see on yours, but you might not have picked it with the cowl. The gills on a Death Cap don't touch the stem, and from what I can see of yours there's a distinct separation.
Anyway, don't panic - just don't eat it and don't let anyone little touch it in case they lick their fingers and wash your hands after touching it. Also don't put it down near anything you're going to eat as the spores are poisonous too.
And of course, I might be wrong - there are loads of fungi that I can't identify.