A "golden oyster block" refers to a pre-inoculated substrate block specifically designed for growing Golden Oyster mushrooms (Pleurotus citrinopileatus), typically made from a mixture of sawdust and grain spawn, ready to be placed in a suitable environment to produce clusters of bright yellow, fan-shaped mushrooms with a mild, nutty flavor; considered a good choice for beginner mushroom growers due to its reliable fruiting and attractive appearance.