A lovely yellow mushroom! Sprouting out from our potted cactus.
A quick glimpse underneath revealed lemon yellow gills.
I couldn't find anything like it in the Collins photo guide (Sterry & Hughes) or the illustrated guide (Buczacki et al). But then spotted the Plantpot Dapperling Leucocoprinus birnbaumii in Phillips' Mushrooms.
It's a match!
Plantpot Dapperling is a tropical/subtropical species which can be found in Britain in heated greenhouses, or indoors situations like this. A little beauty!
I posted these photographs on the British Mycological Society Facebook page where this identification was confirmed by Richard Shotbolt.
For the record
Location: Small Dole
Grid reference: TQ2112