The seedpods of columbines have a star-like shape when viewed from the top, and so so the pods of Nigella hispanica -- although I'm only going from pictures and verbal descriptions with the nigella.

Around this time of year you can find a lot of skeletons of Queen Anne's lace, which are somewhat star-like. They might be more effective if misted with silver or gold spray paint. We don't use any color on our things, so we've never tried that.

Finally, there are alliums that dry like fantasic "shooting star" fireworks or sea urchins that might achieve the effect you're after.

sweet gum balls? stars made out of cinnamon sticks - star of David works better than 5 pointed I think - I have one on my tree twined with with metallic cord.