Corydalis may have tubers or rhizomes and resent disturbance when very young. Either sow them in the desired location or thinly plant in pots where they can grow on for the first year before transplanting. Having gone on about all the difficulties of finding plants or seed, the germination or propagation, it should also be emphasized that all is worth the efforts. Corydalis will perform well where few other perennials survive. Once established they do generally seed themselves about in the garden.
Many species do well in lean soil, rock walls and crevices.
Some species will only thrive in dry rocky shade. There are two species growing in the wild here in the heartland. C. flavula , the yellow corydalis, is a small plant of six to twelve inches with pale yellow flowers. If you are not familiar with Corydalis then think of your grandmother's Bleeding Hearts for they both have similar foliage. It sets prolific seed and I would not recommend bringing this species into the garden unless you have a large relaxed woodland setting.