If I could only plant one crop for doves it would be black-oil sunflowers. 

Dove fields throughout the Southeast are traditionally planted with grain crops. While the concept of attracting doves with sunflowers may not be new, it has not always been widely used. When the right conditions exist, especially in the Southeast, dove fields can be the most productive if planted with sunflowers.

To learn more about using sunflowers for dove fields, consider checking out this publication by MSU Extension Service:
Growing and Managing Sunflowers for Dove Fields in the Southeast

The MSU Extension Service recommends planting from early April through early June. Choose your planting date so that seed maturity will coincide with the desired hunting opportunities. For example, black-oil sunflowers mature in about 100 to 120 days, so a mid-April planting date will provide mature seed in mid-August. If the objective is to have an opening-day dove hunt (around September 1 in most southeastern states), following these guidelines will allow for 2 to 3 weeks of dove field preparation before opening day.

Note: Mourning doves are federally regulated migratory birds. Both federal and state laws regarding baiting regulations should be considered when preparing dove fields. Consult with local enforcement officers and the U.S. Fish and Wildlife Service to avoid illegal field preparation.