Very pretty. Looks to me like a burnet rose (Rosa pimpinellifolia, aka Rosa spinosissima).
Itās popularly known in Gaelic as RĆ²s Beag BĆ n na h-Alba (ālittle white rose of Scotlandā). Itās not native to America but is easy to propagate and both wild and cultivated varieties were popularly transported by Scottish emigrants to America, Canada, Australia and New Zealand as a reminder of home. They were often planted on the graves of those who died far from their homeland.