Growing mushrooms is not difficult. I bought oyster spawn at 
Fill up a clean 20L tin with water and straw or dry grass. Heat to 70 deg cel for around 20min. This pasteurizes the straw. I used my woogas stove to heat up the water. 
Let the straw cool down, then add a portion into a thin
plastic bag. Straw will still be wet, wring out excess water. Sprinkle some spawn and the straw and then add some more wet straw. Repeat until the bag is full. 

 Tie the bags and hang in a dark place.

After a few weeks, depending on temperature, the mushrooms will pop out of the bag. Snap off, and more will grow. Expect 2 or 3 flushes.

Enjoy raw, dried or cooked.