It's pretty easy to make a vegetarian sage-onion stuffing, if you like that style. Start with a whole-grain bread loaf or two, depending on how much stuffing you want to make. I have taken to baking the bread myself (in a machine) and adding the sage right into the dough, rather than sprinkling it on afterward. But obviously either route works. Saute an onion and a few sticks of celery. I like butter for stuffing, but you can fiddle with oil instead -- but I'd use canola, not something stronger like olive oil. Meanwhile, cook up a cup of wild rice. It takes about 45 minutes to crack open the kernels. Mix the bread, the rice, the onion and celery and sage, pat it into a casserole, you can add an egg if you want for a little firmness if you're not vegan, douse with vegetarian broth, cover and bake. Take the cover off in the last 15 minutes to crisp up the top.
I add mushrooms to this stuffing, but don't much taste them between the nuttiness of the wild rice and the sage in the bread.
I bet there are lots of vegetarian stuffing options on google. Let us know what catches your eye.
I have a really good vegetarian stuffing recipe that I used when I did Thanksgiving a couple of years ago. (My dad's a vegetarian.) I'll see if I can track it down for you.