I agree with Bonnie, I call them Whimsies also. Also agree with an early 1960s date, although the first one might be very late 1950s. I know the term "Fascinator" is popular now and many new hat collectors and new hat wearers call them that now also. But back in the 1960s (and for decades before that) a Fascinator was a type of lightweight combination scarf and head covering.
From what my years of research tell me, the term "Whimsies" for these little fluffy toppers was invented by the NY milliner Norman Paulvin. Other milliners had other names for these such as "Hat Nips" and "Skol Nips" and a variety of charming nick names. But Whimsies seemed to stick as the most popular.