Heat oven to 375 degrees. Reserve 1 teaspoon taco seasoning mix in small bowl; set aside.
In medium saucepan over medium heat, melt butter. Add onion; cook and stir 3 minutes, or until tender. Add turkey, corn, tomatoes, garlic and remaining seasoning mix. Cook and stir 5 minutes.
Remove from heat. Stir in cream cheese and 1 cup shredded cheese.
Unroll crescent roll dough on greased or parchment paper-lined baking pan. Separate into triangles. Arrange triangles to resemble sun with center open. Press dough where bottoms of triangles overlap.
Spoon turkey mixture in ring where dough overlaps. Fold triangle points over filling, tucking into bottom layer to secure. Continue until entire ring is enclosed. Bake 15 minutes, or until golden brown.
In bowl, stir remaining shredded cheese into reserved taco seasoning mix. Remove ring from oven. Sprinkle with cheese mixture. Bake 5 minutes longer, or until cheese is melted.
Serve with desired toppings, such as shredded lettuce, sour cream and guacamole.