Preheat oven to 325 degrees F. In a large bowl, stir together flour, powdered sugar, cornmeal, thyme, and lemon peel. Drizzle with 2 tablespoons honey; do not stir. Using a pastry blender, cut in butter until mixture resembles fine crumbs and starts to cling. Knead dough until smooth; shape dough into a ball.
On an ungreased cookie sheet, pat mixture into a 9-inch square. Using a pastry wheel or sharp knife, cut into desired-size squares, but do not separate. If desired, sprinkle squares with coarse sugar. Bake in the preheated oven for 25 to 30 minutes or until bottom starts to brown and center is set. Remove from the oven. While still warm, recut the shortbread into squares. Cool shortbread completely on cookie sheet on a wire rack. If desired, drizzle a little honey and sprinkle coarse sugar over each cookie before serving and garnish with thyme sprigs.
Layer cookies between sheets of waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months.