Some friends at work discovered this giant fungi under a tree at work the other day, and I managed to take a few pictures of it before they took it away. I was annoyed that they hadn't left it alone, but I think the gardeners had decided they needed to get rid of it. Unfortunately it is in a few pieces. Does anyone know what it is?

Its huge! I have never seen anything like it before. I have no idea what it is. Why did the gardener have to remove it? He should have left it in one piece.
I'm pretty sure that it's a Giant Puffball, which is apparently deicious when hollowed out, stuffed and baked in the oven (obviously, it helps if it's in one piece

).
Yes, it looks like a species of Langermannia, the Giant Puffball. As TimberWolf pointed out, they are edible, and apparently quite tasty.
Kingfisher
According to wikipedia when the puffball is mature its insides are greenish brown, whereas when it is immature the insides are white. The mushrooms are edible when young, and it looks like that is what you have got.
Don't eat it unless you are absolutely 100% sure though!