As you asked this in *chickens*.. The only time you will have fertilised eggs is when the rooster/cockerel covers the hen. Otherwise they will lay unfertilised eggs .
Well you can buy unfertilized eggs from a farmer or the store and you can buy fertilized eggs from a breeder. Look online for chicken breeders in your area, many breeders sell fertilized eggs. I get some every year and sell the chicks once they reach the age my buyers want.