I thought the unidentified container contained seeds, but after digging up one of the plants to see what it came from, since they looked like begonias, I found a hardy begonia "bulbil" at its bottom. Hardy begonias are gorgeous shade plants which truly are HARDY. I love them...and will have lots of small plants to share! http://www.sustainable-gardening.com/archives/2324
You can see the bulbils in this image:
Here are the plants in bloom: