Amethyst deceivers are small mushrooms which grow in association with coniferous trees.
When they first emerge, they are brightly coloured with the hue of amethysts (lavenderish semi-precious stones). The deception which their name indicates includes their fading with age, adding to the difficulty in identifying them.
These had only just begun to fade, even though they had been around long enough for something to have eaten almost half the cap of the largest one.