Preheat oven to 350 degrees F. Line 1-3/4-inch muffin cup pan with paper bake cups; set aside.
Prepare cake mix according to package directions. Stir in Signet marigold petals and leaves. Fill each cup two-thirds full with batter (scant tablespoon per cup). Bake 10 to 12 minutes or until a wooden toothpick inserted in centers comes out clean.
Remove cupcakes to wire rack. Cool completely. Frost with Butter Cream Frosting. Top with Signet marigold leaves and blossoms. Makes about 32 cupcakes.
Creamy Butter Frosting
Allow butter to stand at room temperature for 30 minutes. In a medium mixing bowl beat butter with an electric mixer on medium speed until smooth. Gradually add 1 cup of the powdered sugar, beating well. Slowly beat in the 2 tablespoons milk and the vanilla. Gradually beat in the remaining powdered sugar. If necessary, beat in enough additional milk until frosting reaches spreading consistency. If desired, tint with yellow food coloring.