One for ID...

[ergot sum]

Great to have access to so many knowledgeable minds. Unfortunately can't say the same for myself hence the request:

Found a cluster of these in leaf litter under sycamore. Pronouncedly umbonate cap; crowded white, ostensibly sinuate gills; white spore print.
Was looking down the Clitocybe [nebularis] or Tricholoma route but no dead ringers. Surely too late for Calocybe gambosa [though apparently not unheard of]. Any suggestions would be much appreciated...

[NickCantle]

I think your Tricholoma diagnosis may be close

[treecreeper]

The inrolled margin suggests Tricholoma saponaceum. Did it smell of soap?

...and welcome to WAB, by the way!

[ergot sum]

Thanks, brilliant way of sharing info. Odour predominantly 'mushroomy' but there is a tinge of bleach [not sure if that counts as soap]. According to my reference books T. saponaceum usually shows some blushing on the stem or damaged areas which isn't evident on these particular examples, both young and mature [although poor lighting in the photos does convey a reddish hue].