This is the Carolina Anole (Anolis carolensis). These are common in the US, especially in the Southeast. I have seen many in my yard around the fences and outdoor furniture (which is where this picture was taken). Due to their ability to change color, they are sometimes referred to as the American Chameleon (even though they are more closely related to iguanas). Contrary to popular belief, the driving force for their morph is not solely the color of their background. Their color changes due to mood, temperature, humidity, and overall health. Both the males and females have a dulap on their throats, which they can expand in territorial or mating displays (the males is a bright red or pink). They are a good organism to have in your backyard because they do feed on a variety of insects and spiders. They will also bring bird and reptile species that prey upon them to your yard (which as a naturalist always excites). One interesting adaptation that the Carolina Anole has is an autotomic tail, which it can release in the event of a predator attack. This tail will continue to trash around for a few minutes, distracting the predator long enough for the Anole to get away safely. They do regenerate this tail for use in another attack.