We went to Cajititlan today (photos coming) and there were little green pods for sale everywhere. Some were fresh, but lots were steamed. We found some people pulling them off the plants and they sold us a bagful and called them guasanas.
I was totally surprised when I got home and looked them up online to discover they're fresh garbanzo beans (no one said anything about that when we asked multiple people about them, and I never saw them open). There are two little beans in the pods and you can cook and eat them like edamame, or steam them and open them to eat the beans. I'm going to experiment with them tomorrow. Fun find.