Preheat oven to 350 degree F. In a medium bowl combine flour, cornmeal, sage, and baking powder. Set aside.
In a large mixing bowl beat butter with an electric mixer on medium speed for 30 seconds. Add brown sugar and beat until combined, scraping sides of bowl occasionally. Beat in egg yolks, lemon peel, and vanilla until combined. Beat in as much of the flour mixture as you can with the mixer. Stir in remaining flour mixture.
Shape dough into 3/4-inch balls. Place 1-inch apart on an ungreased cookie sheet. Lightly press the tip of your thumb into the center of each ball. Fill the centers with about 1/4 teaspoon blackberry preserves. Bake about 10 minutes or until bottoms are lightly browned. Cool on cookie sheet for 1 minute. Transfer cookies to a wire rack; cool completely. Makes about 60 cookies.