Opiophogon (black grass) has a cascading habit, and would look nice interspersed with Nemesia (white, pink or mauve flowers through the summer). Or if you want a more formal look, a row of Box plants which are evergreen, or Sarcococca, also evergreen but slightly taller, with scented flowers.

If its in full sun, I'd add Lavender to the list to make a low hedge. If you just wanted a very low growing edging, Helianthemums, Iberis sempervirens, Campanula muralis, all evergreen and fully hardy, but prefer a fair bit of sun.

I like geranium sanguinium, but not the white one which refuses to flower for me for some reason.

Don't look much in the winter, though, Steragram, does it.

True - hadn't thought of that.