Geranium phaeum (Dusky cranesbill):
Purple flowers with swept-back petals held high above soft green foliage. Early to flower, reliable and easy. To 60cm. Hardy.
Hosta 'Praying Hands':
Very upright, rippled leaves. Leaves are green, narrowly edged in white and curl up. Lilac flowers in summer. Hardy. Up to 40cm. AGM.
Lathyrus vernus (Spring pea):
Two-tone purple and pink pea-like flowers in early spring. Thrives in shade, even quite dry shade. To 30cm. Hardy.