The common edible mushroom Agaricus bisporus is a basidiomycete that thrives on decaying plant material in the forests and grasslands of North America and Europe. It is adapted to forest litter and contributes to global carbon recycling, depolymerizing cellulose, hemicellulose and lignin in plant biomass. A. bisporus is also an edible mushroom that is widely cultivated and economically important. However, relatively little is known about how A. bisporus grows in this controlled environment in commercial production facilities and utilizes its substrate. Using transcriptomics and proteomics, we showed that changes in plant biomass degradation by A. bisporus occur throughout its life cycle. Ligninolytic genes were highly expressed during the spawning stage day 16 and had low expression during all the other growth stages which could indicate that lignin is not modified after the spawning stage. Our results also revealed differences in gene expression involved in cellulose and hemicellulose degradation between the first and second flushes. This could partially explain the reduction in the number of mushrooms during the second flush.