Becky Shasta Daisy.
A happy flower that lasts and lasts! The Becky Shasta Daisy (Leucanthemum x superbum 'Becky') is the longest-blooming Daisy in the Leucanthemum family! With large, bright white, beautiful ray petals held above its dark green foliage, you can see why the Becky Shasta Daisy was named Perennial of the Year in 2003!
Reaching a height of 2 to 3 feet, the Becky Daisy typically blooms from July to September, and if deadheaded, the blooming time will be extended further... - Becky Shasta Daisy.