Harvesting various types of mushrooms can be very helpful and important for the Foodraise. It's important to note there are multiple kinds of mushrooms you can find in the forest and there is not just one variety.
To harvest a mushroom, use a shovel! Walk up close to the mushroom, hold left click for a bit until your shovel is properly in the ground, and then release left click to dig up the mushroom.
Aratz are a very plain looking brown mushroom. Their smooth dome shape gives them away and small size by comparison sets them apart from the rest.
Kamenas are mushrooms with a very saucer like shape. They are white/tan at the bottom of the shape, have a blue stripe in the middle, and then brown at the top. They can grow to be rather large when fully grown.
A Letjza is a tall brown and white pointy mushroom.