Vegans can eat at Olive Garden! The breadsticks and marinara are vegan and if you want a salad, just ask for no croutons and use oil and vinegar for the dressing (their Italian dressing is not vegan). You can also have pasta (avoid the GF pasta, but standard noodles or Zoodles are ok) with marinara sauce or the minestrone soup.
There are locations in Greenfield, Brookfield, and Menomonee Falls. The details listed here are for Greenfield.