Phylum: Basidiomycota Family: Boletaceae
Chalciporus piperatus (Bull.) Bataille
Peppery Bolete
A common species of broadleaved trees, especially Betula, often in association with Amanita muscaria
References:
Kibby (2011) British Boletes with keys to species
O'Reilly (2016) Fascinated by Fungi
Overall (2017) Fungi: Mushroom & Toadstools of parks, gardens, heaths and woodlands