Steady daddy's Cafe does a great job of providing gluten free options. GF bread is available for sandwiches or toast with breakfast items. They also have many vegetarian options and accommodations for other food restrictions.
New address is 300 E First St Flint MI 48503. There are other vendors that have gluten free options, such as Steady Eddy's and Sweet Peaces Vegan Cafe.
(Mexico at the market) Friendly and knowledgeable staff. I think the only possible gluten could be in sauces. They are all about good service and great tacos. The farmer's market is moving so I didn't include an address