This study was carried out to determine pin head formation time and mushroom yield of Agaricus bisporus on some casing materials. Composts were prepared basically from wheat straw and waste tea leaves using poplar leaves as activator material. In this study, moreover, in order to follow the evolution of the composting process, daily temperature measurements were taken. According to the results of the study, in both compost types, maximum temperature values were observed in the second turning stage. While in the first and second turning stages, inner-pile temperature of the compost was in a tendency of exhibiting steady increase, they are prone to decrease in the following turning stages. In both composts, the period of composting has finished in 19 days. While the fastest pin head formation (13 days) was obtained on wheat straw based compost using peat of Caykara (PC) and forest soil (FS) (50+50; in volume); waste tea leaves based compost using peat of Bolu (PB) and peat of Caykara (PC) mixture (50+ 50; in volume) as casing material gave the fastest pin head formation (13.30 days). While, a mixture of peat of Agacbasi (PA) and perlite (P) gave the highest yield for wheat straw based compost, peat of Bolu shows the highest yield for waste tea leaves based compost.