They look like onion seeds to me. Or something in the onion family at least. lol! I could be wrong though. If you don't pull an onion out for the bulb and let it keep growing. Eventually it goes to flower, looses the bulb, and sends up a main stalk with the seed pod on the top. After it opens up, blooms, and starts to dry up like these ones there are a bunch of small black seeds that will start to fall out.