(Mine's the second one from the right)
Now, I know that a sterling silver key necklace might not look like it followed the traditional bent, but it does: Tiffany's wraps all of their baubles in a little suede pocket. Two of the many reasons why I love my husband: he's incredibly clever and has gorgeous taste. And a reason I love my anniversary, aside from the fact that it celebrates my marriage, is that it's six months away from my birthday (which is always lumped with Chanukkah/Xmas/New Years celebrations). Celebrating and gift giving in June is really refreshing.
Fourth anniversary is traditionally fruit or flowers. See more traditional and modern anniversary gifts by the year here.