I was wondering the fruit stand and grain silo are used for on farmville?
They are simple used for decoration only.
Yes. Those r used in farmville.
They are only there for decoration. A tip for farmville, when you load your farm do not make your character move anywhere from where he loads. Then buy hay bales and surround him with them so there is no gaps. Your character wont be able to move now and harvesting etc is much faster.
They have no purpose except decoration. The only buildings with a purpose are the Chicken Coop and the Dairy Farm. Check the source link for more tips on FarmVille.