You are them! There is hard legal definition, you have read it, and yet "litter" it is whatever you decide it is. If I placed the Mona Lisa on the side of some street, it is legally defined as "litter". Does matter what you think or that it is worth a bazillion dollars. Same as if I dumped a ton of gold bars on someone' front lawn. I could get charged with littering.
Hardly. A store bought display for a grave is not "litter" unless you are the kind of idiot Judge that calls a bee a "fish".