Oceanspray, Holodiscus discolor
I've heard this bush referred to as "ironwood". This is because the wood is apparently very hard and strong. Native Americans used the stems to make digging sticks, bows and arrows, harpoons, spears, and more.
Oceanspray is one of my favorite shrubs. From a distance, the flower bunches are a white blur. When you look closer, however, the individual flowers are spectacular little explosions of beauty.