The pods with four sides are from a poly bloom, from what I understand. Not sure if that means that there is a better chance of the seedlings being a poly or not, but that would be very exciting! I've only had one of them over the years!
I agree that the white seeds aren't ready, or aren't viable, but I'd leave the pod on the scape. The other two sides aren't open yet, so there is a chance that you'll get viable seeds from those two sides. I've never had that problem before though!
I like to go through the garden, and give a little bit of a squeeze on the pods. If you hear a cracking noise, they are usually ready. They may pop open, so be careful and don't squeeze too hard. It's easy to tell with a squeeze if they aren't ready. They will still be very firm.
