Agrocybe (now NOT thought to be Agrocybe at all  ???)
4 October 2004
This mushroom was discovered amongst the Horseshoe Vetch on the lower slopes of Mill Hill.

I think I may have two possible species Agrocybe praecox and Agrocybe molesta. The latter one seems more likely.
 

4 May 2004
 
Mushrooms amongst the grass south of the Reservoir on the 
upper slopes of 
Mill Hill. 

These are probably a species of Agrocybe.

ID suggestion by 
Malcolm Storey (BioImages)

Agrocybe are reported to disintegrate quite quickly. With these it seems they remain firm for a week, but when they suddenly become soapy they will fall to pieces within a day or two if wet. If dry they may dry out if the identifiations are correct.