The man on horseback is a type of pleasant edible mushroom of yellowish colour. It is said to be hazardous in some circumstance, but I am not certain whether that it is because it is easily confused with other toxic mushrooms or because it needs to be cooked before it is eaten. If in doubt, I would steer clear of it. (If gathering mushrooms you must be absolutely certain what you have before you eat them as many are very poisonous.)
