Though sometimes said to be native to Eurasia, Yarrow (Achillea millefolium) is also a North American native. It is believed that the Yarrow now found growing wild here is a hybrid of the two.
Yarrow has been used medicinally by many cultures and also has a long history of use in magic and divination. One example I’ve always found intriguing is the Chinese tradition of using 50 Yarrow stalks to consult the I Ching.
Irish folklore teaches that even just to dream that you are gathering Yarrow foretells of good fortune.
Yarrow was believed to be protective and often worn as a charm. Do you suppose people got this idea from observing that when Yarrow grows in the vegetable garden, the veggies are stronger and more disease resistant?