I was wondering instead of throwing just seeds maybe make the seed balls I have read about ? They look like mud balls and the rain wash them into areas and the dirt helps hold the seeds till the right time.
Just an idea I will think on the flowers a bit . Here we have an oxeye daisy that grows naturally and reseeds well but don't know your climate
I would think there has to be a poppy that grows naturally I can not think of a place that dose not have some kind of wild poppy.
Here along the roadways the state plants cosmos and cornflowers that get no care.
What about sunflowers?