Pleurotus ostreatus
"Omphalotus nidiformis" is a toxic lookalike found in Australia and Japan. In North America, "Omphalotus olivascens", the western jack-o'-lantern mushroom and "Clitocybe dealbata", the ivory funnel mushroom, both bear a resemblance to "Pleurotus ostreatus". Both "Omphalotus olivascens" and "Clitocybe dealbata" contain muscarine and are toxic.