Maturity is reached when the caps are well- rounded and the partial veil is completely intact. Stipe length should be sufficient to permit some trimming without cutting flush to the veil. Quality Indices Good quality, fresh Agaricu s' mushrooms should be white to dark brown.
White forms are most prevalent.
Uniform, well rounded cap with a smooth glossy surface and fully intact veil are indicators of best quality. Stipes are straight and glossy in appearance with an even cut edge. Visible, open gills and absence of a stipe are negative factors. U.S. grades are No. 1 and No. 2. Grades discriminate for maturity, shape uniformity, cleanliness and trim quality.