Hi Sophie,
You're correct, for produce there are less stringent rules when compared to meat, poultry, shellfish, eggs and processed food. However the Nutrition Services person is still liable and should serve food from a reputable source when it comes to produce..
Most garden guides are just that, a "guide" or protocol(s) to serve garden produce. So in 2012, I created a School Garden Food Safety Training and Documentation Manual. It was edited by about 50 people from all over the country and vetted by our State Health Dept. Inspectors. It's still the only example I see of a manual that actually documents your process of serving produce safely from your school garden. Of course it's written with Oregon in mind, but surely other states could adapt it as well for thier state.
you can find it here: https://www.oregon.gov/ode/students-and-family/childnutrition/F2S/Pages/SchoolGardenFoodSafety.aspx
------------------------------
Rick Sherman
------------------------------