Most omega-3 eggs that you buy in the store are produced by chickens who are given flax meal and/or fish meal in addition to grain. They're better than eggs from chickens who get nothing but grain.
But ideally, try to get eggs from a farmer who lets the birds roam on pasture, eating bugs, worms, and greens. They will have plenty of omega-3, and taste 100x better than the store-bought omega-3 eggs.