This grower is sure of this plant identification.
Needs dividing as it has outgrown the space it's in.
Achillea genus (Yarrow). There are about 85 species of Achillea. They are mainly upright perennials, some of which are semi-evergreen. They will produce fern-like foliage, often with hairy and aromatic large, usually disc-like flower heads which will bloom mainly in the summer.
They are fully hardy and will tolerate most soils but grow well in a sunny, well drained soil. The taller species and cultivars will need staking. Tall species and cultivars need staking.
Borders and rock gardens. Flower heads may be dried for winter decoration. Suitable for coastal conditions.
Used in traditional medicine to staunch bleeding and to raise temperature to increase sweating. Yarrow's use as a medicine may stretch back to 60,000 BC, based on the evidence of plants found in a Neanderthal burial site.