Corydalis cheilanthifolia, C. lutea and C bulbosa(solida?) do very well in the South. The first 2 species are easily started from seed and are prolific seeders, once established, but in 20 years, have not had one seedling from C. bulbosa. C. ochroleuca was twice a short lived perennial for me.
None of mine seem to require a special location or soil, however the C. lutea & C. bulbosa are in shade. C. cheilanthifolia springs up everywhere, shade, sun, raised beds, clay banks, under shrubs, hedges. in the lawn, potted plants, etc. I don't mind, because it looks attractrive wherever it appears.

Wow! Thanks for the info, Georgia. Do you have any idea where I could find seed for cheilanthifolia?

I am unsure of my source of C. cheilanthifolia, but could have been T & M, which I stopped ordering from several years past, because of generally poor germination rate of their seed.
I am linking a seed company in Texas that has decent ratings at Dave's GWD. but I have had no personal experience with them. Click on their New for 2007 link, for C. cheilanthifolia.

Here is a link that might be useful: Digital Raingardens

Seed corydalis lutea and corydalis sempervirens are available from JL Hudson, Seedman-PO Box 337-La Honda, CA. 94020. jlhudsonseeds.net. I've purchased many seeds from JL Hudson; packets are generous & germination high. The title of the catalog is "The 2008 Ethnobotanical Catalog of Seeds"--black&white, looks homemade, no photos but great info..Corydales Papaveraeceae (formerly FUMARIACEAE) easily grown mostly hardy perennials, freely blooming in poor soil & full sun or part shade. Some slow to germinate & best sown in fall, the annuals best sown in spring or fall. The author says the catalog is "uncopyright" so they won't mind my quoting here!