Achillea millefolium
Knee-high clumps of creamy flowers stand atop a narrow stalk. Each yarrow flower has a sweetly classic daisy shape to it – and like a daisy, it is actually many flowers. If you look close you’ll see the demure inner “disc” petals surrounded by the flashy outer “ray” petals.
In the southwest, yarrow is sometimes called Plumajillo, or little feather, because of its delicate plume-shaped leaves. It is listed as being mildly toxic by the California Poison Control system, but historically has been used as a tea to treat colds, nausea, cramps, hives, measles and kidney ailments. Yarrow (Achillea millefolium) also was used externally to treat cuts, stop nosebleeds, and as a hair wash to prevent baldness!
Flowers Of Marin 