Wait until a national Chinese Holiday then bring them something traditional. They'll be suprised, hopefully in a good way. But i don't think there are anything in March, i think there's one in the summer, its to do with some dragon shaped rowing boat racing thing (no, not the Oxbridge thing !). On that day, Chinese make these Steamed leaf wrapped rice thing with Chicken and mushrooms inside. The legend has something to do with a dragon, someone drowned, and throwing those wrapped rice thing into the river to feed The dragon so it wouldn't eat the person drowning or something. My Myth/Legend on this is very rusty but it is a national holiday. The one after that, would be the Full moon in August in the Chinese calendar, Something call the Moon cake is eaten. You can get them in Chinese Supermarkets and Bakery. Buy them a Tin of that to surpise them.
Or just turn up at the door and introduce yourself, they are still people