Line a baking sheet with waxed paper and grease the paper.
Melt margarine in a large saucepan over medium-low heat; stir marshmallows into melted margarine until mixture is smooth. Mix green food coloring into marshmallow mixture until color is dark green.
Gently stir regular and sugar-frosted corn flakes into marshmallow mixture until coated. Working quickly, drop the warm corn flakes mixture onto prepared waxed paper by tablespoon. Grease your fingers with butter and gently shape the mixture into green wreath-shaped forms. Decorate wreaths with cinnamon candies while still warm. Set wreaths aside to cool and set.