This is a plant I transplanted from a wooded area that is thriving in my yard. Some have white blooms while others have pink.
Your plant is called an obedient plant, because you can actually move the flowers around the stalk with your fingers and they stay where you moved them. It is a kind of mint, not the edible kind, and the scientific name is Physostegia virginiana. It is not very common in South Carolina, and it usually grows in more sunny areas. I don’t think I have seen a white flowered form.
Steven Hill, Ph.D., Botanist SCNPS