Sustainable and certified organic MyCO2 Mushroom Kits automatically generate carbon dioxide as a byproduct of fungal decomposition. One recyclable MyCO2 bag provides enough carbon dioxide for flowering plants in a 4-foot-by-4-foot grow room with cycled exhaust. Once activated, the Grow Mushroom Kit fruits reishi mushrooms and generates a flow of CO2 over a 180-day period. The Bloom Mushroom Kit fruits oyster mushrooms, which are more aggressive and generate a heavier flow of CO2 over a 60-day period once activated. MyCO2 Mushroom Kits include a safety hanger, reusable clip, and compostable light-shielding box and medium.