Closed Cup Mushrooms are baby button white mushrooms (Agaricus Mushrooms) grown into ‘teenagers’. Though the head of the mushroom is less round, the pinkish gills of the mushroom are still covered with a thin white skin, so the ‘cup’ is still ‘closed.’
The flavour is very mild.
This is the most popular stage of growth at which white mushrooms are purchased.
If allowed to grow further, the mushroom will become an open cup mushroom.