>>19934464You can use just about any grain to grow mushrooms. Millet, popcorn, oats, wild bird seed, popcorn, rye berries, etc…Popcorn is the easiest to work with because it’s the grain that’s the hardest to fuck up. It absorbs excess moisture in the jars, retains its shape after being soaked and boiled (minimal burst grains), easy to break up in the jar while the mycelium is colonizing it… Not to mention that popcorn is prepared for human consumption so the grain is much cleaner out of the package.