Over the years mine have been happy to accept both chocolates and champagne [a generous year] so unless your hospital has some draconian policy I don’t see why not.
When public employees have a gift policy it is usully because they could potentially confer benefit on the giver. For example a local government officer who could award contracts. This does not really apply to nurses and in any case a box of chocolates would hardly constitute a bribe! (However I could be persuaded to do many things for chocolate!)