[Mycology] which fungus is this?

[Arnaud_Hulskes At hotmail.com]

Hi all,

In the plant standing for my window there is a beautiful mushroom
growing.
Does anyone have an idea which species this is? I'm very curious about
it.
For a photo see:

http://img218.imageshack.us/img218/3164/paddestoeltjeinplant031zt0.jpg

Many thanks in advance,

Arnaud