She got inside by donning a sunbonnet and pretending to be an old woman.
From the timesunion.com
I wore a sunbonnet passed down from my maternal great-grandmother, kept my hair in braids like Laura Ingalls, and occasionally called my parents Ma and Pa.
From the online.wsj.com
By planting the seeds as soon as the soil thaws and dries out a bit in spring, you'll have the best chance to enjoy the exotic fragrance of these sunbonnet-shaped flowers.
From the dailyherald.com
More examples
A large bonnet that shades the face; worn by girls and women
A hat (bonnet) worn for protection from bright sunlight