Fourth anniversary gifts are traditionally fruit and flowers, so last month Aaron gave me a cherry necklace and a necklace with flowers on it. I was especially enamoured with the flower necklace because he said I could interchange it with other pieces.
When we got home from the beach he got me another one, because really, what is the point of having a interchangeable necklace when you don't have another one to swap it with?
They are called Switch Tags and they come with an outerband and a two sided inner tag you can change out.
There are also Switch Rings that are interchangeable two piece rings. They were only $5 and he got me two of those also. They are my favorite bits of jewelry now and I enjoy fiddling with them in meetings.