There are many customs and traditions that go along with weddings but this well known custom comes from and Old English rhyme, "Something olde, something new, something borrowed, something blue, and a sixpence in her shoe." Brides throughout the decades have incorporated this in their wedding attire, for tradition and superstition. It symbolizes: continuity, optimism for the future, borrowed happiness, fidelity, and good fortune.

Your "something old" could be an heirloom, a bible, jewelry, a piece of your mothers gown.
Your "something new" could be your dress, shoes, undergarments, jewelry, hair pins.
Your "something borrowed" should be borrowed from a happily married couple.
Your "something blue" can be discreet maybe ribbon laced through your garter, combined with one of your "old, new, or borrowed."
Penny in your shoe? Not many adhere to this tradition any longer but superstition is if so it is to ensure a life of fortune.