Gardenburger is the brand name of a veggie burger. The company makes a variety of vegetarian and vegan products and meat substitutes. According the the company's website, the original Gardenburger is made from mushrooms, onions, brown rice, rolled oats, cheese, and spices. Gardenburger is a registered trademark of the Wholesome and Hearty Foods Company. Other products such as Chick'n Grill and Veggie Breakfast Sausage also contain soy protein and wheat gluten.
Although all Gardenburger products are vegetarian, some of them are not vegan and include animal-derived ingredients such as eggs or dairy products, such as milk and cheese. Their vegan burgers are the Black Bean Chipotle, Flame Grilled, GardenVegan (which is also soy free) and Veggie Medley; the vegan specialties include BBQ Riblets, Chik’n Grill, Herb Crusted Cutlet, and Veggie Breakfast Sausage. Their website also lists heart positive, wheat free, gluten free, and soy free dietary preferences as well as vegan. 
Gardenburger labeling does not exclude the possibility of their products containing genetically modified soy.
- http://www.gardenburger.com/eat-positive/special-diet/index.php "Dietary Preferences: Vegan, Heart Positive, Wheat Free, Gluten Free, and Soy Free product lists"
- http://www.gardenburger.com/community/articles/index.php#No_Caged "No Caged Chickens" Policy