Oat Grass

Arrhenatherum bulbosum ( Bulbous Oat Grass )
Also called A elatius.

'Variegatum'
Forms a clump up to 2 feet with white variegated foliage.
Looks great in the landscape when massed.
Hardy zones 4 to 9 in full sun to partial shade.

Arrhenatherum calamagrostis ( Silver Spike Grass )
A stunning perennial grass, reaching up to 3 x 3 feet, that is native to Europe.
The spectaular silvery-green flowers are borne on abundant spikes during the summer.
They turn to tawny-brown during autumn.
Hardy zones 5 to 8 in full sun on well drained soil. Clay tolerant. It thrives in the Rocky Mountains but does not enjoy the hot humid east, especially where nights are warm.