Please don't dig it up for your home garden.
Purple loosestrife is indeed beautiful.
However, it is considered an invasive non-native weed that is endangering the environmental balance of our wetlands areas. Unfortunately, it tends to crowd out the native species that provide shelter, food and cover for animals and birds. It has an extremely aggressive root system, and spreads prolifically, particularly in moist, swampy areas. Some garden centers do sell a sterile variety of purple loosestrife, but there is debate about whether it is truly sterile if it comes into contact with the wild variety. If you do buy the garden center variety, don't plant it near waterways or in boggy areas.