Keep your ordinary and special chickens in your Farmville Chicken Coop! Keeping chickens in chicken coops allows you to find Mystery Eggs!
Here is the Farmville official announcement:
"Every now and then your chickens will lay Mystery Eggs! The more chickens you have in your coop, the more likely you are to find Mystery Eggs everyday!
Each chicken only lay mystery eggs that are the same color that they are. More chickens of a particular color means a higher chance of getting that color of Mystery Egg!
The only way to get Brown, Black and Golden Chickens are from Mystery Eggs that your friends share or by buying them in the Market."
To see more details about the chickens inside your chicken coop, just click on your coop and then select Look Inside. A window will pop-up showing the kinds of chicken, level, number of kinds of chicken and what color of eggs each kind lays.
Level 1: Chicken - Chickens lay Premium White Mystery Eggs
Level 2: Brown Chicken - Brown Chickens lay Uncommon Brown Mystery Eggs
Level 3: Black Chicken - Black Chickens lay Rare Black Mystery Eggs
Level 4: Golden Chicken - Golden Chickens lay Treasured Golden Mystery Eggs