My mother-in-law just sent me a Facebook message telling me the "menu" and wrote who is bringing what. Then she said, "You don't have to bring anything, but you can if you want to." Clearly, she is hinting that she wants me to contribute. I am going to offer to bring a variety of non alcoholic drinks because I don't want to cook.
I decided to make a few suggestions (paper/plastic wear, sweet tea, or pumpkin pies) and ask my mother-in-law what she would like us to bring. Her response was: "Paper-plastic wear and/or sweet tea would be great!" I showed my husband the messages and he said he would pick up some plates, napkins, cups, and plastic wear.
Just wanted to update and thank everyone for the advice!