Entoloma serrulatum - Blue Edge Pinkgill
Small, about 25-30mm mushroom. The identification based on the description from:
Entoloma serrulatum is a blue-black mushroom (unusual color for a mushroom), and the radially fibrillose cap that often breaks up into fine scales near the centre helps distinguish this lovely Entoloma from other bluish species. The pallid gills have blackish edges.