Place mustard seeds, allspice berries, whole coriander seeds, and red pepper flakes into a small glass jar with a tight-fitting lid. Shake to combine. Add ground ginger to seeds and shake again. Sprinkle crumbled bay leaves over spice mixture and place cinnamon stick halves into the jar. Seal and shake to combine. Mixture can be stored in the tightly sealed jar for up to 1 month without loss of flavor.