In a 10- to 12-inch frying pan over medium-high heat, stir cumin seeds until fragrant, about 1 minute. Add oil, garlic, onion, and bell pepper; stir often until onion is limp, about 3 minutes. Add corn, jalapeño, lime juice, and lemon juice; bring to a boil. Remove from heat; stir in shrimp. Chill, stirring occasionally, until cool, 15 to 20 minutes.
Stir in tomato and cilantro.
Place salad greens in a large bowl. Spoon shrimp mixture over greens; mix to serve. Add salt and pepper to taste.