Oxytropis gracilis is a charming Canadian native flowering now. It appears to prefer a dry spot and seems easily grown.
Pasithea caerulea has grasslike leaves and comes from Chile. It grows to about 60cm and seems to be tolerant of drought.
Sophora davidii is a deciduous shrub from south west China. It forms a neat rather prickly mound and has blue and white pea flowers in late May and June.