Simple, get a stuffed bear, stick a card in his hand (make sure you put something down there sentimental) and stick him in the eco friendly trash can.
Don't get too sentimental but you want to show her that shes been doing good, sometimes corny stuff works but i try to come up with original ideas. And flowers are best when there is no occasion. Being spontaneous, especially after you've been together for awhile, is what keeps relationships going.