I'm posting some screen shots of the new artwork for the farms and a couple of different crops you can grow, these will show wheat and cotton, though there are many other crop types.
Wheat is used in the bread making industry, it is first converted into flower by a miller. Cotton is used by gnomes to make thread which can then be woven into clothing.
When you build a farm plot and specify what to grow there, your gnomes will plant the seeds and then you'll slowly see the plants grow (animated), then when a plant is fully grown a gnome will come to harvest it and it will be added to your resources.