Meh. If your company doesn't trust you with a box of doughnuts...
Company policy says you can accept anything of nominal value. You can't accept cash or cash equivalents.
I don't think there's a single engineer at work who has used a more expensive vendor, a sketchy technology, or anything like that because they got a free lunch or even a ticket to a Wild game.
That you can't have a doughnut speaks more to what your company thinks of you than what your company thinks of ethics.