Light brown flattened cap, scally cap, crowded gills, thick white stipe.
Custered at the base and found on a compost heap
No identification made yet.
No interactions present.
It is difficult to be sure from the photo but if it had gills it could be an Agaricus but if it had pores Polyporus squamosus would be a good bet
Just noticed you say crowded GILLS so Agaricus probably. Put it on a piece of white paper overnight and hope for a dark brown spore print.
Lat/Lng: 53.1, -4.1
OS grid ref: SH6167