I have only had success finding seeds on zonals. When the heads dry you will see spikes sticking out. At the base of the spikes is the seed. The success rate I've had is so/so but if you collect a lot you'll have some plants.

bloomorelse, here's some photos of geranium seeds and pods. You've got to be quick to harvest them and time it just right or the seed capsules have opened and you've lost your seed. I was making daily visits to g. nodosum this year trying to gather enough to sow...

(I've grown hardy geraniums from seed by sowing fresh seed on moist potting soil, covering with chick grit, and leaving the container outdoors here in this mild climate. Have not done the more tender types)

Here is a link that might be useful: seed pods and seed

Oh thx suz and Mor,
I was just trying to collect these for someone for a swap! Hard to find little suckers!
Karen