1. Preheat oven to 425°. Place a jelly-roll pan in oven while it preheats.
2. Combine thyme, dried plums, shallots, garlic, and squash in a large bowl. Drizzle with 1 tablespoon olive oil, and sprinkle with 1/4 teaspoon salt; toss to coat. Remove pan from oven. Arrange squash mixture in an even layer on pan. Return pan to oven; roast vegetables at 425° for 10 minutes.
3. While vegetables cook, sprinkle pork chops with remaining 1/4 teaspoon salt and pepper. Heat a large skillet over medium-high heat. Add 1 1/2 teaspoons oil to pan; swirl to coat. Add 2 pork chops; cook 3 minutes or until browned on one side. Transfer to a plate. Repeat procedure with 1 1/2 teaspoons oil and remaining pork chops. Remove squash mixture from oven, and place pork chops, browned side up, over vegetables; return to oven. Roast an additional 20 minutes or until vegetables are tender and pork chops are desired degree of doneness.
4. Combine arugula, lemon juice, and remaining 1 teaspoon olive oil in a large bowl; toss gently to combine. Divide arugula mixture among 4 plates. Top with pork chops and roasted squash mixture; pour any pan juices over the top.