To confirm that all these specimens within a common population growing close to a trunk of Salix alba are all Psathyrella candolleana. A small doubt is arising because the gills and spore print is (maybe) too much chocolate brown and usually, it is lighter and has that bit of a violet-mauve hue.
Spores
(6.7) 7.1 - 8.4 (8.7) × (3.7) 4.3 - 5.1 (5.5)
Q = (1.5) 1.55 - 1.8 (1.9) ; N=26
Me = 7.8 × 4.7 ; Qe = 1.7 ; Ve = 90
Another option is Psathyrella bivelata, said to have dark tufts of veilar remnants on the pileus
Alcune specie interessanti del Genere Psathyrella
Thanks for your opinions.