So other than peas and green beans, I haven't grown beans yet.
When you grow beans that are typically stores as dry beans (ex. Black beans, kidney beans, navy beans, pintos, etc.) is there any difference in harvest or post-harvest of the beans whether you plan to use them for food or for next year's seed?
When you grow them, no. And you can grow seed for peas or green beans simply by leaving those on the plant longer until they get to a hard, dry, finished/mature seed state, rather than the immature state those are normally eaten in.
Commercially they may (or may not) be treated in ways that don't help their function as seed (such as a high-heat processing step, or the "splitting" of things like split peas, which are dry and fully mature peas.)
Of course, if you are not using open-pollenated varieties, what you get next year may not resemble what you grew this year (standard issue with hybrid seeds of all sorts.)
