sunflower seeds

I pulled out some seeds from a sunflower head, laid them out on a towel for a week and put them in a jar without a lid. All the seeds smell and are full of mold now. They been in the jar for two weeks. What did I do wrong?

When do you cut the head of the sunflower for seeds? The sunflower is not dead yet but the flowers itself is rotting and soft in some spots of it. I did see the seeds are in there. I am new to sunflowers and was wanting to save seeds for next year and eat some as well. But not sure if it’s...