A Coprinus species, some of which are edible.
The other day I posted a picture of the Ear Fungus and Canadian Chickadee asked if it was edible. The simple answer is no – it would be like chewing rubber. I must also point out that eating any wild mushroom or fungus is a hazardous pastime. We have a friend currently in hospital with serious kidney failure from having eaten just a small portion of a single wild mushroom.
If it is a Penny Bun it is edible
but if it is one of the related Boletus species it could be poisonous.
The Fly Agaric may or may not kill you but it's what
the Vikings used to eat to make them go berserk in battle
so I wouldn't recommend trying it!
The Branched Oyster Fungus - an edible species
but I'd still prefer to buy mine in the shops
People in the UK often buy simple little books like the Collins Wild Guide to Mushrooms and think that they can thereby identify what they see in the woods. This guide has 240 species in it. There are at least 15,000 species of larger fungi in the UK. The RSPB has recorded 3136 on its reserves alone. So, as you can see, a guide which only shows 250 species is not particularly comprehensive. It’s fine for identifying them for fun but not where your life is at stake.
Another edible species - the Chanterelle - or is it??
In addition fungi are very variable and if you watch the fruiting body of a particular species from day to day you may see it gradually change shape and colour and texture so that after two or three days it looks entirely different.
The Wood Blewit - also edible but then again it could be a...
At first glance this looks like a Field Mushroom
but it is actually the poisonous Yellow Staining Mushroom.
So my advice, unless you are a qualified mycologist or have years of experience of recognising a particular species, would be leave wild fungi alone and buy your mushrooms in the shops.