A friend gave me half of her 14" diameter humongo Prince mushroom (Agaricus augustus) Made some fabulous burgers with large slabs of the mushrooms in them. They were really good. Just whack off some thick slices, saute them in butter or oil on both sides, and trim to fit the burger. I used lettuce, mayo and ketchup. It would also be good with avocado or fennel.
Alison Gardner is an avid mushroom enthusiast, cook, botanist and potter.