Yarrow (Achillea millefolium) flowers from July onwards well into October. The white form is a common weed/wildflower of grassy places.

 The pink variation is slightly less common but still widespread. I saw both growing in the verges outside the village of Gosmore at the junction of Thistley Lane and Half Handkerchief Lane. I can guess how the former got its name but what is the legend of the Half Handkerchief?