Here is a real simple DIY centerpiece project that I did over the weekend that ANYBODY can do really easily. This sort of craft would be cute for a sunflower themed wedding. I love the little round bowls that you can buy for real cheap anywhere. There are so many things that you can do with them for centerpieces.
small round glass vase
yellow dye (or whatever color)
artificial sunflower (or whatever flower you choose)
Leaves from artificial flower
Add water pearls to your glass vase. Soak the water pearls in water until the expand. Drops the dye in the water pearls and stir (you may want to drain some of the excess water out from your vase using a paper towel). Position artificial leaves into the side of your vase. Add flower on top. Easy.