I created a 3 part video series that will show you how to grow oyster mushrooms from mushrooms that you purchase at the store.
Here's a quick run through on how to do it.
You'll need to find a store that has fresh oyster mushrooms. What you're looking for are mushrooms that have the white fuzzy stuff (mycelium) near the base. That is what we'll be growing our mushrooms from. You don't need too many....only about $1 worth.
Next you'll cut the stem butts and put them in a jar with used coffee grounds. After a few weeks the mycelium will have taken over the coffee grounds and at this point we add the jar of mycelium to pasteurized straw. A bale of straw will cost you about $4 at a garden center. You can grow them in any container but most people prefer clear plastic bags.
At this point you'll keep your container in a high humidity chamber. After 14 days you'll see that the mycelium has taken over the straw. At about day 19 you'll see tiny mushrooms forming. You'll be harvesting on about day 26.
I have more details on my website: http://www.tomorrowsgarden.net/content/how-grow-mushrooms-home
This first video shows what I have accomplished with my last grow. The last 3 videos show step by step on how to do it.