Stropharia rugosoannulata first impressed me by the size. Stamets books often show this mushroom with little kids sitting on them. They are happy in woodchip, but the most promising reward is there partnership with vegetables. Collected between Sydney and the Sunshine Coast at least. Botanical Gardens, Parks with woodchip.
There are several variations- white capped or reddy-brown capped or in the video below elaborately patterned.