The weather in the Bay Area has been unusually dry this year. I got to play golf two weeks in a row. The first course had sunflower seed shells fairly close to the hole. The second time I played, the sunflower-seed enjoyer was a stranger in my group that the pro shop put with my threesome.
The first week, the sunflower seeds looked fairly moist, so the shell spitter was likely a few groups ahead. I have to say it was a bit gross to have to deal with the shells. At least the guy in my group was "considerate" enough to spit the shells away from the hole and he did this may be only for the first few holes. He stopped having them by the middle of the round.
I enjoy sunflower seeds too, but I wouldn't think of spitting them onto the green. If you enjoy those seeds, have a cup that you can spit the seeds into. That way, every one can enjoy a shell-free round of golf!