Hi Em,
It's not a defined lesson plan, but we did Victory Garden posters one year for summer camp. The lesson involved discussions about how during the World Wars, some foods were rationed and others were being grown in quantity to help feed soldiers (e.g. wheat during WWI), and that people were encouraged to plant Victory Gardens -- in the US, France, and the UK, so more food could be diverted to the war efforts. Then the kids looked at the propaganda posters. Afterwards, they made their own posters to encourage a modern Victory Garden.
The upshot, from a classroom perspective, is that this can be very cross-curricular.
These are some of the WWI posters in the Library of Congress:
These are WPA/World War II and deal with food in general: