Argemone polyanthemos (Annual pricklepoppy) (or white pricklepoppy) does not appear in the Wildflower Center Master Taxa List. This does not mean it never appears in our gardens, but perhaps the list has not been updated. We're not sure what you mean by "featured" but the gardens tend to have mixed beds with plants native to Central Texas (which the pricklypoppy is.) We do know that while they are not native to Travis County, TX, where the Wildflower Center is, they are native to Williamson County, just north of Travis. Wildflowers do not tend to notice county boundaries so we are sure there are some growing in this area; in fact we have noticed areas where they were growing during their normal blooming times of April to October. They are annuals and will self-seed in the Fall if weather conditions have been favorable.
As for where they can be viewed and photographed, you may have to travel a little. According to this USDA Plant Profiile Map, they do not grow natively in Louisiana at all. There might be some scattered around, but your soils and rainfall are not quite the same as those in Texas; the whole point of choosing plants native to an area is because they can grow more easily somewhere that the soils, climate and rainfall are those to which they have been accustomed by centuries. Texas is the nearest state having native pricklepoppies to Louisiana, and the nearest Texas county to East Baton Rouge Parish is Madison Co., TX, still pretty far across the state of Louisiana. If you follow this plant link, Argemone polyanthemos (Annual pricklepoppy), to our webpage on the plant, you will learn more about its growing conditions, etc. You will note that this is pretty much a plant of the Western U.S. From Colorado Wildflowers, here is a site with more information and pictures.