Of Sunflowers and Birds

I planted sunflowers a while back, put them where they'd have plenty of sun, watered. . . and not one even came up. Not one. Meanwhile, the birds who stuff themselves at our feeders, drop seeds willy-nilly and we have sunflowers everywhere. These happen to be on the north side of our house where they have shade much of the day, yet they thrive regardless of my attention of lack thereof. We have bird-planted sunflowers in my flower bed where they get watered. They are here at the edge of the bank, where they get ignored. They sprouted up in my failed vege garden and are sprinkled up and down the berm that hides the water line. I'm thinking that rather than plant anything, I'll just put seeds of whatever I want in the bird feeders and see what happens!