The easiest way to grow mushrooms at home is with a five gallon bucket full of coffee grounds, and some Oyster Mushroom spawn. Spent coffee grounds can almost always be obtained free from a nearby coffee shop. Oyster mushroom spawn can be purchased online from Amazon or from a mushroom lab near you. Detailed instructions for putting together a five gallon mushroom farm can be found http://www.stormthecastle.com/terrarium/how-to-grow-mushrooms.htm
How to collect mushroom spores. This sounds like an interesting project to do with the kids, or yourself. You can make some unique art, and the article also has a link to teach you how to grow your own mushrooms.