Mystery boxes in Zynga's "FarmVille" feature exclusive items that can't be acquired elsewhere in the game. Mystery boxes may be available for purchase through the "FarmVille" market, found through normal gameplay or received as a bonus gift when you buy a Zynga game card. "FarmVille" items and game content are frequently updated, and mystery boxes are available for a limited time. Check the in-game notifications or the Zynga community forums to find out if the game currently contains mystery boxes.
Instructions:
1) Press the "Market" button in the "FarmVille" interface. Select "Decorations." Press the left or right arrows until you find the mystery box. Press the "Buy" button to purchase it.
2) Plow the fields of your farm to discover a locked mystery box. It will appear in the "Gift" section of the interface. Place the mystery box in your garden and click on it. Choose "Get Passcode." Enter a valid email address and select "Yes" when asked if you'd like the code emailed to you. Enter the passcode provided in the email to unlock the mystery box.
3) Buy a Zynga game card for Farm Cash, the "FarmVille" currency, through an authorized retailer during a mystery box promotional offer. Click on the "Add Farm Coins & Cash" tab in the game and click on the link to redeem your game card. Enter the pin number on the card to add the currency to your account and receive a mystery box.
Tips & Warnings
Mystery boxes available from the market typically cost 16 Farm Cash.
Source: eHow
