Maybe Entoloma clypeatum ...

[BubikolRamios]

Grassland. I already seen pink/red stuff, on white cap, in past, more evenly, dotted distributed on entire cap, Can't find image of that. Any comment on pink stuff ?
Did test, damaged a bit of cap, no change in color.

[Svampskogen]

Rather Volvariella. Please show the whole fruitbody and not only parts of it (Volvariella has a volva at it's base). Pink stuff could be bacteria.

[BubikolRamios]

Sorry, bottom was not cut off only in image but from mushroom too. Upon your suggestion, not the one I meant originally, that one is still hiding ...

on Piptoporus betulinus, don't know how I figured Serratia marcescens at the time.