Trim and chop 2 bunches dandelion greens, watercress or baby kale. Cook 3 slices chopped bacon until crisp; transfer to paper towels using a slotted spoon. Add 1 each sliced garlic clove and shallot to the drippings; cook, stirring, 1 minute. Add 3 tablespoons cider vinegar and 1 tablespoon sugar; stir until dissolved. Add the greens in batches, tossing to wilt. Season with salt and pepper; top with the bacon.