There is a recent Fungimap Agaricus pamphlet that I have not viewed I don't know if any other moderators have, perhaps it may have in it some useful information that will enable the identification further.
@Hejor1 that's OK, but odour and colour change can assist with ID. Some Agaricus sp. have a distinct chemical smell while other will smell of almonds or anise, some will stain red and others yellowish; just something else for you to be aware of and hopefully this will assist you with future ID's.