quick, what flower it this?

i have photographed viburnum many times. but always in winter. it is one one of the few plants that offers me translucent red berries all winter long. i love how the snow piles up on top of the berry drupes, looking very much like a beanie hat. we call viburnum highbush cranberry, even thought it is not a true cranberry at all. it is native however.  i pass this particular viburnum at least once a week. so, i was a bit stunned today when i saw these flowers. if i did not know that his particular bush was indeed viburnum, i would have assumed those flowers were hydrangea flowers. i love that i can still be stopped in my tracks with wonder, after all these years of doing STILL.

ameican highbush cranberry (either Viburnum opulus var. americanum or Viburnum trilobum)