No, not virtue signalling. It's a good idea, but it needs to be suggested carefully, for, as gillybob says there are, in many schools, Parents who will be in need of the food banks themselves, and the last thing schools would want to see would be people struggling out of a sense of obligation to give, when in reality, they can't afford to.
A nice home made card (nothing elaborate, either, a drawing is enough) would be appreciated rather than boxes of chocolates, mugs and notebooks. It's a tricky one, though, as children like to give something, but competition does sometimes creep in and also, some of the children who don't have anything to give can feel upset about it, despite assurances from the teacher that it doesn't matter.