Two good plants for dry shade. Wood Spurge (Euphorbia amygdaloides var. robbiae) has glossy dark green leaves throughout the year and throws up luminescent lime green and yellow flower heads through spring and early summer.
 Stinking Iris (Iris foetidissima) is also evergreen though its sword-like fronds look a bit wan after winter. It's tough as old boots yet the flowers in early summer are pale and delicate of hue. More striking are the bright orange/red berries which appear in autumn and hang in clusters for months before they drop.