Wildflower nurseries in various parts of the country can supply plants indigenous to your particular locale. They will also advise you about growing needs, and will even sell you the proper soil if you are unable to dig it up somewhere.
Poor-soil plants can also stand a certain amount of inattention from the gardener. Light eaters include nasturtiums, gail
lardia, gayfeather or blazing star (Liatris), flowering flax, Iceland poppies, moss-pink (Phlox sublaia), sun-rose (Helian-themum), harebell (Campanula rotundifolia), rock cress (Arabis), four-o'clocks, spider flower (Cleome), cockscomb, hardy ageratum, star of Texas, stocks, sweet sultan (Centaurea imperialis) and Swan River daisy (Brachycome). All of these flowers bloom more abundantly if not given a rich diet, and for the most part they won't be bothered too much by drought. Most herbs also fit into this category, and they will be more richly flavored if grown in poor soil.