Feathertop Grass

The plumes are the point. Pennisetum villosum carries soft cream bottlebrush flower heads on arching stems from midsummer, and a planted drift of it catches low light in a way very few grasses manage.
It is an Ethiopian highland species, tough, drought tolerant and undemanding, and it spreads by short rhizomes. That spread is worth checking against local weed listings, since it is a declared or listed invader in parts of Australia and California.
Feathertop Grass gives soft movement and long seasonal interest on dry ground, provided its spread is acceptable on the site.