This grower is sure of this plant identification.
9 cm pot. A taller growing variety to 15 - 20cm
Rush lily, Pigroot, Satin flower, Blue-eyed grass
Sisyrinchium genus (Rush lily). This genus consists of about 90 marginally to fully frost-hardy species of annuals and rhizomatous perennials.
They are fully to half hardy and will prefer sun, although they will tolerate partial shade and well drained but moist soil.
Suitable for coastal conditions.