It has been very warm and wet lately - the best climate for mushrooms.
People rush to the forests to pick them. Yes, mushrooms can pretty much be picked anywhere as long as it is not within sight of a private dwelling. This is possible due to the Swedish Right of Public Access.
Berry and mushroom picking is a national past time.
Of course, one can make money selling mushrooms to Italian companies that have established themselves in Sweden to collect Karl Johan mushrooms (Boletus edulis) or what the Italians call porcini mushrooms. This mushroom is rare and expensive in Italy, but plentiful in Sweden.