The origin of “something borrowed” stems from the following rhyme:
Something old, something new
something borrowed, something blue
And a silver sixpence in her shoe.
Each item in this Victorian-era poem represents a good-luck token for the bride. It was believed that, if she carried all of them on her wedding day, her marriage would be happy. "Something old" symbolizes continuity with the bride's family and the past. "Something new" represents optimism and hope for the bride's new life ahead. “Something blue” is an object that symbolizes faithfulness and loyalty. "A Silver Sixpence In Her Shoe," is a blessing for wealth. Since sixpences are difficult to find, any silver coin makes a sufficient substitute—but these days a penny is also considered good luck! (And the cheapest part of your wedding!)
"Something borrowed" is usually an item from a happily married friend or family member, whose good fortune in marriage is supposed to carry over to the new bride. The borrowed item also reminds the bride that she can depend on her friends and family.
Your friends and family are normally thrilled to help you with this “something borrowed” item; however, it may be a bit tricky deciding what to borrow from whom. Why not consider borrowing things from multiple people to keep the peace? A few ideas: mom's pearl necklace, the earrings your grandmother wore at her wedding, your parents' (or a friend's) home for the wedding or reception, money from your parents or his (for the wedding or honeymoon), the adorable little bag your best friend carried at hers, your aunt's veil or headpiece, your sister's wedding shoes, an elegant wrap from your future mother-in-law. An extra tip: you can always involved them all in the decisions by being proactive—tell them you’d like to borrow something from all of them, and say you’re excited to leave it to them to arrange who gives what. A bit sneaky, but you avoid being the “bad guy” altogether.
Truly, really anything can be borrowed, but whatever it is don’t get too attached; the tradition also states (in small print) they all need to returned. (Don’t worry; you can keep my advice!)