Resource Fields
From The Evony Wiki ::The Free Forever Massive Multi Player Real Time Strategy Game
Resource Fields are areas that are located outside the town walls in which a player creates a specific resource producing item. These items are farms, sawmills, quarries, and iron mines.
Each of the resources produced from these fields is used to build or upgrade items within the game, or to create troops at your barracks to defend your city or launch attacks.
To create a resource field, select the City view. You will see lighter spaces in the area in front of your city that indicate available resource fields. The number of resource fields you have is determined by the level of your Town Hall.
In one of the available spaces, select the Build option. A window will appear with the resource fields listed. If you are unable to create one, make sure you have the available resources in your city and that the field is available to build on.

