here, here, here, and here.
Found at Couleurs.
Addendum: A tip of MY hat to shibori78, who discovered a similar hat in a photo of a young woman from lower Saxony:
fleurdecoucou's Flickr photostream, where it is accompanied by this text:
"Phot. Fr. Wehde, Bückeburg - Stadthagen, Germany, ca1905-10. Young woman wearing the traditional Westerten (Bückeburg) costume (Bückeburg is a small town in Lower Saxony, Germany, on the border with North Rhine Westphalia.)"