Are they on the food program? Is so, I'd report them anonymously. Do they have a menu posted for parents? Does it coincide with what's served? IOW do parents know what their child is being fed? Is the center covering up? Lots of things to consider here, whether it's fraud, laziness. I believe you can report anonymously. And I'd also look for a different place to work; it feels very sketchy to me. Just curious what's on the menu for another day?
PP is right that it's allowable but terrible, by the food program. IMO I think the FP should have more rules on things like hash browns and frozen potato products(maybe they did change it?). I only serve sweet potatoes(never white) once in awhile because it feels like so many starches in one meal counting them as a veggie.