Thanks George. Perhaps I didn't wait long enough or planted them too deep.
The seeds I planted weren't powdered, but they were about 1/4" solid, black---about 40 were released when one seed pod opened. In general, where are the seeds located in the pods, and how are they released? Now, I also have "powder" like seeds which I shook out of the top part of the pod, but they could just be dirt. I'm re-trying planting both types following your instructions.

I'm also going to buy some seeds on line and try planting them as well until I get the harvesting thing right. I went to the park and picked up about 100 pods last month right after they bloomed. How long are the pods good for that are lying in the ground?

Fingers crossed!