It is common yarrow, and its very much a spreading plant in the lawn
with fern like leaves, and has a head of flowers that is white to
pinkish-white flat-topped composite flower heads.

When in the bare ground it does grow tall.

As it grow with rhizomes in the lawn, its very hard to get rid of.


Are you sure it's yarrow? That's rather a tall plant for a lawn weed.
But if it is yarrow, just pull it up and compost it ( it's shallow
rooted and a very good activator of compost heaps)

Janet