The problem with this, as my dad was quick to point out, (he had already thought this through--I had to learn through experience,) is that birds are messy creatures and the majority of the seed ends up all over the ground. Then you end up having a massive weed issue to deal with.
I had been trying to keep up on the weeds, and was looking for a better place to put the bird-feeder, when we went on vacation for half of the summer. When we got back our little birdseed weeds had grown a tiny bit.
Apparently our gardeners thought that the plants were a) intentional, b) pretty cool looking, or c) too much of a pain to keep pulling up.
They are pretty cool looking plants, so we decided to let them live while doing a little reasearch on them. I believe we have grown ourselves a miniscule crop of millet. Millet is an ancient grain that has been used in many ways for thousands of years. Since we are studying Ancient Civilizations in school, this was fun information. We found out that it is ready to be harvested when golden brown...and since it is mostly already there, it looks like the kids have some threshing to do. I am thinking that perhaps I should have titled my post "How to Turn an Accident into a School Project".