Why can't I use my foodstamps to purchase food bearing plants here?

I would recommend setting up an appointment with the store manager and providing the USDA guidelines.

That's outrageous. I've never had that issue at this store. I'm going to guess ignorance is the reason, on the store's part-- someone isn't paying attention to the food stamp rules. Maybe show them this next time: fns.usda.gov/snap/eligible-food-items