My begonias have a lot of seed pods and I was reading online that the seeds are like powder. Can I store them in the pod until I'm ready to use them or should I remove the pod from the ziploc bag and try to remove as many seeds from the pod as possible?

I'm very new to seed collecting so thank you in advance for all of your help!

Yes; the imaptiens should have light brown/brown seeds. The white ones aren't ripe yet. If they have snapped off the branches, they weren't. If they were ripe, they would've already popped open when they hit the ground. The ones I've picked have always been still on the branches, and are bright green and fat. I usually collect them by snipping off the branch the pod is on, and then gently put them into a cup, which a lot of times enough to pop them open. They aren't called 'touch me nots' for nothing!

As for the begonias, definitely let them get nice and brown until they are practically falling off the branches before gathering. Then, dry them well and store them until you are ready to sow, sometime in early winter. Mind you, I've only gotten a few plants from many pods. They are indeed dust size, and very tempermental. I rubbed the pods gently over the soil and hope for the best, but germination is slow and really tiny. But if you do get some to germinate, be patient and you will be rewarded with beautiful plants that are tougher than the store bought ones. I put mine out in the winter sun on a windowsill and they never burned in the summer sun.