chicken has iron, im not sure if it has as much as say, a steak, but i believe it does have some. do you have reason to believe your son is anemic? is he bruising easily, lethargic ect? a simple blood test can be done at the doctors to check his hemoglobin levels and determine if he is indeed iron defiecient.
egg yolks are high in iron. dried fruits are also high in iron, and cooking in cast iron pans will increase iron in the food you eat from them. greens have iron in high amounts, such as kale, spinach, broccoli ect.
the iron in fortified products like cereal is not easily assimilated and used by the body as it isnt really in its natural form. but floridix is great, good tasting and all, but i dont know if its good to gove iron to a kid unless they for sure need it.