yes bird seed has got hemp seeds in it,lol when i was a little boy i grew one from bird seed,it was like jack and the bean stalk.it would not stop growing up,man that plant was super looking.i impressed all my mate back then with it lol.
it turned out to be a male plant so i killed it stone dead
but yer why would you ever wont to grow one of these things,they will not do a lot for ya,well maybe give you an headache or make you feel sick