The seasonal mushrooms in Animal Crossing: New Horizons will only be available for a limited time in the game. It varies on your location, too. For those in the southern hemisphere, you can obtain these during May, and if you live in the northern hemisphere, it’s in November.
While mushrooms are available, you will find them growing around the base of hardwood trees. You can freely pick them up if you see any of them, and there are several varieties, such as skinny, round, and flat mushrooms. The most difficult to obtain are the rare mushrooms. These can only be harvest at specific locations, and under certain circumstances.
For those looking to acquire a rare mushroom on your island, you have quite a bit of ground to cover. The first thing you need to do is to ensure you have a perfect rating for your island. Once you have that, you need to ensure you have a tree stump on your island. After that, you should find a glowing dot underneath this stump, similar to if you were looking for a place to dig up bells to make a money tree.
These are buried underground, unlike the other mushrooms, which make them a bit more difficult to locate. After you have a decent understanding of where to find them, ensuring you grab plenty to add any of the seasonal mushroom DIY recipes. Of the ones available, only one requires a rare mushroom to complete.