Spotting

Here is the list of Armillaria species: http://en.wikipedia.org/wiki/List_of_Arm... if this is any help to you (it doesn't have pictures for all the mushrooms).

I can see the Blewit resemblance, however these appear to be growing from from solid wood (possibly live), rather than wood debris and they are too clustered. I believe they are mature Armillaria species. Gill and stem shots would help determine which.

Looks like blewits - Clitocybe sp.