 Use of this mushroom as a food source also seems to have existed in North America . A classic description of this use of A. muscaria by an African @-@ American mushroom seller in Washington , D.C. , in the late 19th century is described by American botanist Frederick Vernon Coville . In this case , the mushroom , after parboiling , and soaking in vinegar , is made into a mushroom sauce for steak . It is also consumed as a food in parts of Japan . The most well @-@ known current use as an edible mushroom is in Nagano Prefecture , Japan . There , it is primarily salted and pickled . 
 Use of this mushroom as a food source also <a href='uninflect' title='1'><mark>seems</mark></a> to <a href='been_done' title='2'><mark>have</mark></a> existed in North America . A classic description of this use of A. muscaria by an African @-@ American mushroom seller in Washington , D.C. , in the late 19th century is described by American botanist Frederick Vernon Coville . In this case , the mushroom , after parboiling , and soaking in vinegar , is made into a mushroom sauce for steak . It is also consumed as a food in parts of Japan . The most well @-@ known current use as an edible mushroom is in Nagano Prefecture , Japan . There , it is primarily salted and pickled . 
Use of this mushroom as a food source also seem to done existed in North America . A classic description of this use of A. muscaria by an African @-@ American mushroom seller in Washington , D.C. , in the late 19th century is described by American botanist Frederick Vernon Coville . In dis case , the mushroom , after parboiling , and soaking in vinegar , is made into a mushroom sauce fir steak . It is also consumed as a food in parts of Japan . da most well @-@ known current use as an edible mushroom is in Nagano Prefecture , Japan . dere , it is primarily salted and pickled .