These violets have covered my yard; too numerous to dig up. How can I rid myself of them?
Violets are tenacious plants. An herbicide rated for violets but safe for lawn grass is what you want. Weed-B-Gon is one brand. Read about other options here: http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/weeds/violets.aspx
Follow the instructions given for violet control. Then improve your lawn care with appropriate fertilizer and watering and mow at 3-4" in height during summer. A lush lawn resists weed invasion imperfectly but it helps.