Mushrooming Season is an event that occurs in Animal Forest, Animal Crossing, Animal Forest e+, City Folk, New Leaf, and New Horizons. It is officially mentioned as an event in all of the games, with the exception of Animal Forest+ and City Folk. As the name of the event states, it is the season where mushrooms will grow the best at.
In Animal Crossing, the season occurs from October 15 - October 25. Four or five mushrooms can be found around the town starting from 8am. The mushroom can be sold to Tom Nook for a hefty price (see Mushroom). One mushroom disappears every 15 minutes , meaning that all mushrooms will disappear by 9:00 AM.
In City Folk, all throughout the month of November, the player can find mushrooms at the base of trees. Some mushrooms are actually furniture from the Mushroom Series. There are five different types of mushrooms; Elegant, Rare, Flat, Skinny, and Round. These different kinds of mushrooms can be sold to Tom Nook ranging from low to a high amount of Bells.
In New Leaf, Mushrooming Season occurs in autumn. Round, Flat, Skinny, Rare and Famous Mushrooms are found near all tree stumps and trees. On each day, one of these reveals itself as a part of the Mush Series. Harvest Festival is the last day of this season. The rest of November there will no longer be mushrooms spawning as such.
In New Horizons, Mushrooming Season starts on the first day of the last month of autumn (November in the Northern Hemisphere, May in the Southern Hemisphere) and lasts until the end of that month. Skinny, Flat, Round, Elegant and Rare Mushrooms are available, which are used in seasonal DIY Recipes (alongside Acorns, Pine Cones, and Maple Leaves).