Amazon.com : Gymgit 15-Pack Mushroom Grow Bags, Heavy Duty 6 Mil Polypropylene Mushroom Substrate Bags, Large Size 8" X 5" X 20" for Mushroom Cultivation, Spawn Bags, and Sawdust Fruiting Blocks :
Sterilized Oat Grain Spawn Bag - 4lb – Cellar Door Mushrooms