Deceivers are a quite common species of mushroom which are the fungal equivalent of birdwatchers little brown jobs. They are indeed also small and brown, and easily confused with other species.
Amethyst deceivers would be the same in a monochrome world. In fact, their pale purple (amethyst) colour is unique. Nor are they particularly common. This picture was taken on the only occasion I’ve ever seen some. They were in Himley Plantation, a Woodland Trust woodland which supports lots of interesting fungi. It was September 2014 when I saw them. When I revisit the wood, I look carefully round the area where they were, but there’s been nothing since.