Campanula lactiflora (Milky bellflower):
Clusters of blue flowers on tall stems in mid-summer. Ideal for filling out borders and adding height. Fills out quite quickly too. To 1.5m. Hardy.
Leucanthemum x superbum 'Wirral Supreme':
Tall form of Shasta daisy with white flowers and multiple shorter petals around the golden centre, making an attractive frilly effect. Hardy. Up to 1.5m.
Sisyrinchium idahoense 'Album':
White star-like flowers with a yellow centre, grass-like strappy foliage. Prefers a sunny spot with good drainage. Hardy. Up to 15cm.
Sporobolus heterolepsis (prairie dropseed):
Fine deciduous grass with green foliage in summer turning golden. Graceful flower heads in late summer. Needs sunny spot in well-drained soil. Hardy. Up to 1m.