Identification: help identifying mushrooms found on UBC campus

I live on campus and just returned to my condo after four months - my roommate was supposedly taking care of the garden but she apparently missed a few corners.... I found this massive cluster of mushrooms under my rose bush. When I dug them all out I had about a 1/4 of a garbage bag and I'd estimate over 5lbs. Any idea what they are? I've tried searching online photo albums but no matches so far and I'm not that familiar with BC mushrooms.

Thanks

 

They have that Lepiota eye on the cap, they're growing on composting vegetation by the looks of things, I see some possible yellowish staining, and the gills appear white, and the veil is pretty thick and prominent so I suspect you might have Chlorophyllum rhacodes.

What color is the spore print? When you cut the stalk does it stain orange-brown?

There's also Agaricus preclaresquamosus that grows here, in victoria, that looks pretty similar.

Here's the thread where I asked for help IDing C. rhacodes: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=59216

 

Looks like Leucoagaricus americanus (as Sabetts pointed out, they are most definitely in the Lepiotaceae).

 

I'd vote for Chlorophyllum rhacodes. I see some orange bruising on the stems in the middle photo; so they probably stain the same way when cut.

 

I should have explained my rationale but the distinctive swollen stem keys me in to Leucoagaricus americanus. Secondarily, I always find these in dense clusters, while I do not find Chlorophyllum rhacodes growing in dense clusters like these. Here is a close up of the stem (note swollen base and the bruising) http://www.mushroomexpert.com/images/kuo2/leucoagaricus_americanus_03.jpg

 

I didn't know that Leucoagaricus americanus was found in BC, but I see that the website Pacific Northwest Distributions for Macrofungi lists it for BC. So it could be that species. It would be easy to verify by cutting the stem. If it stains orange to red, it is very likely Chlorophyllum rhacodes.