For my family's holiday gatherings, where my grandmother was similarly protective of her "one-butt kitchen" (she claimed there was room only for one butt in there), every woman who was the eldest grownup in her household tended to bring the same signature salad or dessert to complement the main dish and side dishes my grandmother made. 

Grandma's age group brought their favorite homemade pickles, jams, and so forth.  Mom's generation brought pies, fruit salads, that ambrosia stuff (white creamy salad with fruit salad, coconut, and who knows what else in it), and green salads.  Once I was old enough to insist on bringing something even though I was part of the grandkids' generation, I brought homemade dinner rolls; my cousins brought various cookies and snack mixes (like Chex mix).

My mother's fruit salad was so pretty and festive.  She would cut a pineapple in half lengthwise, carefully scoop out the flesh (leaving the shells intact with their pretty green tops), and mix the chopped pineapple with seedless grapes, apples and/or pears tossed with lemon juice, orange segments, and maraschino cherries.  Then she spooned it all back into the little pineapple-shell "boats" and brought it along.  It was always wonderfully refreshing next to the heavy traditional feast, and seemed very welcome.  (I would use fresh or frozen cherries these days, as I've developed a personal aversion to maraschino cherries, but the latter look gorgeous and work well in the recipe).  I think she often added banana slices right before serving, tossed with lemon to prevent browning.

It's pretty with mint leaves scattered over, if you like mint-- or not!  Just put it in a vessel where it won't tip over on you and wrap it in plastic wrap.  Sometimes Mom would bring the fruit salad in an airtight plastic thing and tip it into the shells just before serving.  That made for easy transport.