AEGVIIDU, Estonia—Don't let Angeelika Kang fool you. She has built a reputation as the Baltic answer to Martha Stewart with her willingness to show amateur bakers how to whip up camera-ready cakes. She shares her best recipes in popular Estonian cookbooks. But there are deep secrets she isn't going to divulge, like how she finds her wild mushrooms.

Ms. Kang, 42 years old, is passionate about one of the nation's treasured pastimes: preserving dewberries, tomatoes, cucumbers and other edible items that can be freely gathered...