Many edible fungi have look-alikes that are inedible or even poisonous. Of these six pairs of fungi, the upper species in each case is a popular edible mushroom while below are look-alike inedible fungi some of which are deadly poisonous.
It is particularly difficult to identify immature mushrooms with certainty if you intend eating them. Because many identification features are not visible until the cap expands and the gills are clearly visible, only those fruitbodies that are mature or nearing maturity should be collected for food.