The visible mushroom is a fruiting body. The fungus also grows as mycelium: a network of fine threads through its growing material. A farmer first establishes that growth, then manages conditions in which fruiting bodies can develop. A bag without mushrooms may still be in its growing stage.
In this Button illustration, the cap, gills and stem belong to the fruiting body. The network below represents mycelium in compost. The separate top layer is casing. Other cultivated mushrooms may use different materials and may not need casing.
For your own crop, record two different observations: development of the growing material and development of the mushrooms. Do not describe both simply as “the crop looks white”. A drawing cannot distinguish cultivated mycelium from contamination in your bag.