Growing conditions, and who knows what else is going on, can at times result in atypical examples of species. I must admit this sighting is much more robust to what I'm used to seeing. Though the other characteristics seem to tie in. At time this species can be vary from the dark colour in the caps in your examples through browns to very pale brown. Thus the species name followed by 'group' which indicates that we don't know everything about this species and it is most probably a combination of a number of similar though slightly different species we are seeing. One of the many challenges of identifying fungi!!!