leucocoprinus birnbaumii or I'm a dutchman
Back when I lived somewhere nicer, one of the aspidistras got all this weeeiiirrrd looking toadstools thing going on. They grew pretty big, and were a leering & malevolent sulphurous yellow sickly hue etc.
Kinda put you off your tea when they were sitting in the pot next to you being all fungusy & potentially toxic.
Writing in July of 2010, I have since found out that they're also called Lepiota lutea, have an egregiously dull common name - Yellow parasol mushroom, and a reasonably large number of other people have had the same, "What in the name of crikey O moses is THAT! growing in my plant pot?" type experience.
So I got the good folks at Roger's Mushrooms .com to see if they could tell me what they were. And they fairly unequivocally decided that they were Leucocoprinus birnbaumii.
I've just checked back at Roger's, and they appear to also be called Leucocoprinus flos-sulfuris.
It was one of those oddly life-affirming moments that you can suddenly stumble into on the ninternent, where people get together and tell each other helpful things about toadstools, instead of trying to steal each others identities, insulting the living daylights out of total strangers, or flogging you some Viagra substitute that you didn't know you wanted.
Only slightly poisonous, it turned out. Mushrooms are funny.
I just remembered: The Roger's Mushrooms lot said there was no common name for this type of mushroom. So I suggested "Brimstone Treacles"
Seeing as they seem to need one. They are sulphur yellow (kind of), they go all syrupy when they lie in water once they've died, and they're possibly poisonous, like the awful character in the Dennis Potter play of nearly the same name. It's a bit tenuous, but I quite like it, even though I do say so myself.
Writing as of July 2011, I have just realised that I spelt the latin name wrong originally. It's Leucoco, not just Leuco, as I'd put. I still think my name's better.