In a medium bowl, whisk together the eggs, dill, and salt and pepper to taste.
In a large skillet (nonstick, if available), melt the butter over medium heat. Add the fennel and cook until tender, about 5 minutes. Stir in the peas and radishes; cook 2 to 3 minutes more or just until crisp-tender. Add the eggs. Cook, without stirring, until mixture begins to set on the bottom and around edges. With a spatula or large spoon, lift and fold the partially cooked egg mixture so that the uncooked portion flows underneath. Continue cooking over medium heat for 3 to 4 minutes or until egg mixture is cooked through, but is still glossy and moist. Remove from heat. Stir in feta. Serve immediately.