New Chronicles of Rebecca by Kate Douglas Wiggin

Rebecca was used to this sort of errand, for the whole village of Riverboro would sometimes be rocked to the very centre of its being by simultaneous desire for a yeast-cake. As the nearest repository was a mile and a half distant, as the yeast-cake was valued at two cents and wouldn't keep, as the demand was uncertain, being dependent entirely on a fluctuating desire for "riz bread," the storekeeper refused to order more than three yeast-cakes a day at his own risk. Sometimes they remained on his hands a dead loss; sometimes eight or ten persons would "hitch up" and drive from distant farms for the coveted article, only to be met with the flat, "No, I'm all out o' yeast-cake; Mis' Simmons took the last; mebbe you can borry half o' hern, she hain't much of a bread-eater."

So Rebecca climbed the hills to Mrs. Came's, knowing that her daily bread depended on the successful issue of the call.