It is not Chestine Gowdy but a white with red streaks. An old walmart or lowe's bargain from many years ago. I have divided the original several times and tossed many roots for lack of need. It has very large blossoms with a hint of fragrance. I will try to find a pic of it. Really nice but I have 2 other mature clumps. Free to anyone willing to pay postage. Mail me?
This is from 2013 and is typical of this particular cultivar as best I can remember. I have a few named cultivars similar to this but they have more pale pink.