I can see why you suggested Lepiota s.l. However, here you see an irregular fragment of white tissue on the cap surface. That's part of a membrane (the universal veil) that wraps the entire mushroom when it's still in the button stage. As the stem and cap grow that veil ruptures and in this case leaves irregular fragments on the cap surface. In your photos you can just see one fragment. A view looking down on the cap would show it more clearly. Lepiota and its relatives don't have universal veil, though you often see neatly, concentrically arranged scales (the result of the skin of the cap splitting as the cap expands) - but not random, irregular fragments.