The first wedding anniversary is the paper anniversary. You could buy a framed original edition of a newspaper for example of your partners date of birth or tickets to a show.
The second anniversary is the cotton anniversary. Of course you could buy underwear or lingerie but maybe matching bath robes is more your style.
The third anniversary is the leather anniversary. This is one that may or may not be acceptable to your partner but it can be fake leather if you prefer. Anything from leather belts to a leather cell phone cover to a leather strapped watch is appropriate.
The fourth anniversary is the fruit and flowers anniversary. If you often send flowers then this might be the opportunity to try something a little fruitier.
The fifth anniversary is the wood anniversary. Instead of thinking about a wooden carving or piece of wooden furniture you could take a long anniversary weekend in a romantic log cabin and get away from your hectic lives for a few days.
The sixth anniversary is the iron anniversary. I am talking about the metal, not the appliance unless you want to risk buying a new iron for your anniversary. A better option may be...