yes, it is as big as his hand
You can go and purchase a mushroom growing kit or make your own.
First you will need a shallow container, something like a plastic storage bin works well.
Mix equal amounts of sterile compost, potting soil and peat, filling your container with a 2-to-3-inch layer. Reserve 1/4 cup for use later. Smooth the top layer of soil as uniformly as possible.
Now gather some shroom spores. If you know your wild mushrooms then go for it. However, if you are not sure, it is best to purchase your mushrooms. Grocery stores are fine to purchase them, as pesticides are not used in mushroom production. Once you have them you need to do some spore printing. Remove the stems and with gills down, press you mushroom caps down on a piece of clean white paper. Set aside and wait 12 hours for the spores to be released.
Mist the soil of your new kit with water enough to make the soil glisten. Scatter the spores over the top, then sprinkle your reserved soil over the top. Place plastic wrap over the top, poking several holes in the plastic for air flow.
Place this into your closet or anywhere that is is relatively dark and cooler, no more than 75F no less than 55F. Keep the soil lightly damp by misting every few days.
Mold will appear on the soil. when this happens (usually in about a week), remove the plastic wrap and cover with a light towel. Mushrooms could appear in as little as 10 days. Harvest your mushrooms at will.
You should be able to get mushrooms for 6-8 weeks using this homemade kit.
How to sterilize your soil/compost;
Place soil in an oven roasting bag (like those turkey bags you see at the store). Add a bit of water (dampened) and tie off the bag. Place the bag on a cookie sheet and poke a hole for a meat thermometer. Heat oven to 200F. Bake soil until the dirt temp reaches 160-170F. (if soil reads higher, reduce your oven heat). Bake for 30 minutes. Remove and cool completely before using.