This looks like a group of slightly immature Coprinellus disseminatus. Originally described as Agaricus disseminatus (see Persoon, Syn. meth. fung. (Göttingen) 2: 403 (1801)) then as Coprinus disseminatus ((Pers.) Gray, Nat. Arr. Brit. Pl. (London) 1: 634 (1821)) and finally as Coprinellus disseminatus (Pers.) J.E. Lange [as 'disseminata'], Dansk bot. Ark. 9(no. 6): 93 (1938). If my suggested identification is correct, as the cap matures it goes from a creamy yellow to a dull whitish gray with darker vertical striations.