Sunflowers

I have never had any great success with growing sunflowers. I'd plant the seeds and get as far as seedlings and small plants and then they would die, fall over or be eaten! But this year I have had beautiful tall sunflowers for the first time.The strangest thing is I did not plant sunflowers at all this year , in fact not for several years. So where did they come from? I wondered would it be the birds as I have lots of birds in my garden. Or would it be my home made compost?
Early in the year I noticed some weeds in my tubs and baskets and discarded them. I had used home made compost when planting them up. The I noticed similar "weeds" and one taller specimen hidden behind another plant and wondered if it could be a sunflower.I planted it out  and in a few days I knew it was a sunflower so I decided naturally not to discard any others. So that is how I have sunflowers everywhere in pots and on ditches etc. But the mystery is where did they come from. I think it is from my compost . Is that a good sign of my composting abilities or not.I took great delight in seeing the bees feasting on the flowers in the sunshine this summer . A good flower to attract bees to your garden. Great for pollinating!