I also use the big triangle pick for strummin' & flatpickin' but--

I have seen oldtimers using the feathers & once asked them to show me how they did it. They just whipped out a little pocket knife & scraped off the fluff part of the feather not quite half way down the feather. The feather is held with the end that was stuck on the goose, & they'd whip the other end back & forth across the strings. They said they always used goose feathers. I like them best, too.
When I used to play at a living museum circa 1870's, in period attire, I often used the feathers like this except when I was playing with other musicians & needed to use a pick to be heard.   
I like to give children the opportunity to try strumming, but have noticed that smaller children are often shy about it when I offer them a pick. When I offer them a feather instead, they almost always want to try playing. They do seem to prefer strumming with the other end of the feather, I have noticed.