Went for a walk in the woods on Saturday and was delighted to find a big patch of Amanita mushrooms of various shapes and sizes pushing their way up through the leaf litter. (Perhaps Amanita muscaria, but there are several similar-looking species, and my mushroom ID skills are very limited.) These mushrooms, with their red/orange/yellow caps and white polka dots, are the ones that feature prominently in fairy tales and Mario video games.
The polka dots are actually called “warts,” and according to this glossary of fungus terms are fragments of the ball of tissue that enclosed the immature button mushroom before it sprouted. They can come off – for example, they can be washed off by rain. Additionally, as the mushroom ages, the cap shrinks and flattens, further exposing the gills underneath. Here’s a photo I took recently of what is probably another Amanita mushroom, but an older one (and maybe also a different species).