This grower is sure of this plant identification.
Ox-eye daisy, Moon daisy, Marguerite
Leucanthemum vulgare (Ox-eye daisy). The flowers have pretty white flowerheads which are borne in early summer. They are clump-forming perennials and are about 75cm tall. This plant is often found in the wild in Northern Europe.
They will grow well in a perennial border or garden bed in full sun or morning shade with a moderate fertile, moist but well-drained soil.