Symphyotrichum ericoides 'Snowflurry' (Heath Aster)
This is a cool North American native plant! Shade, sun, dry soil, rocky soil, clay soil, it doesn't matter. A tough plant that will attract loads of pollinators. 'Snowflurry' stays low to the ground, not reaching more than 12", and will be covered in white flowers giving the look of mounds of fresh snow in early fall.