Winsor McCay's Little Nemo in Slumberland
An eiderdown (according to the Collins English Dictionary) "a thick warm cover for a bed, made of two layers of material enclosing a soft filling" and thus not necessarily stuffed with the epidermal growths of the Common Eider for which the garment is named.
Eider duck female and chicks (with their eider down intact -- source: Thomas Reich)
As I fried hashed browns and veggie bacon in a wok and brewed coffee in the French press, my thoughts returned to eiderdowns, and to the songs which have celebrated... or at least mentioned them. "It's an eiderdown kind of day," as they say.