Some edible mushrooms are very similar in appearance to poisonous kinds and may grow in the same habitat. Edible mushrooms are known to be safe to eat because they have been eaten frequently with no ill effects. Poisonous mushrooms are known because someone ate them and became ill or died. There is no test or characteristic to distinguish edible from poisonous mushrooms.
This indicates a need to identify with certainty one of several of the proven edible species and pick and eat only those positively identified. To see a visual list of the 36 types of edible mushrooms click the link below
(Picture Credit: preparedforthat.com)