f2.8, 1/500, ISO 80. I see these roundish mushrooms frequently, and have photographed a few, some of them singly and some in clusters. But there are difficulties with these things - often the mostly-white mushroom is in bright light, which obscures some of its surface detail. The other major problem is the surrounding grass or brush, which rarely provides a good aesthetic. But this time everything worked - the mushroom surface detail, the light leaking through the background, etc.