Mushrooms With white gills tend to be poisonous. So are Individuals which has a ring around the stem and those with a volva. The gills of Psilocybe semilanceata are dim brown. More youthful shrooms can have greyer-looking gills, and more mature shrooms may have gills that look almost black. Gills: https://psilocybinuk.co.uk/product/field-mushroom/