There are many kinds of fungi around now and I think this is a Parasol Mushroom  which has not yet opened into a parasol.  It has some similarities to a young Shaggy Ink cap in the extra.  I have included a few others seen in the last week and have tried to identify in my guide to 410 mushrooms and toadstools and think they might be Yellow Stagshorn,  Wrinkled Coral, Earthy Powdercap and Fly Agaric but quite possibly are wrong and am happy to be corrected.