Sometimes I carry seeds around with me in my pocket just in case I see a place to poke one. Two of my favourites for this are beans and sunflowers. They are both biggish seeds and good to poke in all over the place.
When I walked past this unused concrete water trough (below) I decided it was begging to be filled up and used to grow climbing beans because it had a wire fence beside it. Climbing beans are also good to poke in at the feet of sunflowers and corn, a marriage made in heaven so to speak. I guess I'm just a natural born poker.