False saffron milk cap mushroom growing in short grass near conifers, West Park. The green colour of the cap develops as the mushroom matures. When it’s fresher, the cap is the yellow shade which can still just be made out around the rim. At that point, it is often confused with the saffron milkcap, also known as the delicious milkcap.
That species is, as the name implies, a foodie favourite. This, more common one has a bitter, unpleasant taste.