Prepare rice according to package directions; adding collard greens and corn to water in the last 5 mins.
Preheat oven to 450°F. Drain rice and vegetables; transfer to saucepan. Stir in black beans, pumpkin purée and taco seasoning.
Spoon 1/3 cup rice mixture down center of 1 tortilla; sprinkle with 2 tbsp Monterey Jack cheese. Roll up tightly. Place seam side down on parchment paper–lined baking sheet. Repeat with remaining tortillas, filling and cheese. Brush taquitos with olive oil; sprinkle with remaining cheese.
Bake for 10 to 15 mins or until tortillas are crisp and cheese is melted.
For homemade taco seasoning, blend 1 tbsp chili powder, 1 tsp ground cumin, 1/2 tsp dried oregano, 1/2 tsp garlic powder, 1/2 tsp salt and 1/2 tsp pepper.
Serve taquitos with sour cream, salsa or guacamole for dipping. Garnish with fresh cilantro.