Nomenclatural and taxonomical notes are given on species of Agaricus section Arvenses, together with a key to the accepted species occurring in the Netherlands and adjacent regions. Two new combinations, Agaricus osecanus var. squarrosipes (Bon & Collin) Nauta and Agaricus urinascens var. excellens (F. Møller) Nauta are made. A new variety of Agaricus sylvicola, var. squarrosus Nauta, is described.