If you've just bought/grown/found some mushrooms, and you're curious as to how you can store them for long periods of time, consider the following:
1) Are my mushrooms dried? If you've bought them, they probably are. Have a look. Are they small, withered and hard? If yes, continue to step two. If no, dry them using any of the other desiccant/air dry methods listed above. Ensure that your mushrooms are cracker dry. No moisture, whatsoever.
2) Is there any mold on my mushrooms right now? Look for white fluffy spots. If there isn't any, continue to step three. If there is, throw your mushrooms away, and save your stomach some trouble.
3) Are my mushrooms contained properly? Aim for a sealing bag to hold dried mushrooms. Do your best to squeeze as much air as possible from the bag. If done well enough, the sides of the bag will stick to each other, forming an airtight seal that will help in preservation.
4) Where should I keep my mushrooms? Take a look around your apartment. Is there a cool, dry, dark space where you could keep them, without pets or room mates or other pests finding them? Also, consider putting the bag in a Tupperware, to prevent crushing.
5) Do you remember where you put them? Save a word document on your desktop if you're really forgetful, or if you hid them while you were high.
Following these steps, you can prevent rot and decay of mushrooms for months.