This grower is sure of this plant identification.
Chinese loosestrife, Old gooseneck, Shepherd's crook, Loosestrife
Lysimachia clethroides (Chinese loosestrife). This species produces arching spires of white flowers, they produce decorative ground cover that will grow vigorously.
They will prefer a slightly acidic soil with a good mix of organic matter, they need full sun or partial-shade. You can propagate from seeds or cuttings, or by division.
Cutting bed, border, ground cover, naturaliser