Yellow Fieldcap is a fungus that likes to grow in fields and pastures, but always on or near....... horse or cattle dung !
The picture shows a young and a (nearly) mature specimen.
The young one has a round and convex shape with a distinctive bright yellow colour.
The adult evolves more or less flat and its colour fades to greyish or pale tan, but usually retaining a small yellowish center.
Dutch name : Dooiergele mestzwam
German name : Gold-Mistpilz
Latin name : Bolbitius vitellinus