Best Wishes on your upcoming wedding! I don’t know what your theme or color scheme or budget are, or how “crafty” you are, but here are some centerpieces I’ve seen:
Flowers and/or candles (of course)
Small glass bowls filled with seashells & a votive candle
Live butterflies in little cages with live flowers
Instead of 1 large wedding cake, a small cake on each table
Something NOT to do, live fish in glass cylinders. Don’t know if it was the chlorine or the water temperature, but by the time the ceremony was over all of the fish were dead. Groomsmen were scooping them out before the bride had a chance to see them!
Also, ask your wedding party, friends, and families for suggestions (and assistance putting the centerpieces together).