Many ringneck doves do well on a good wild bird seed mix or small parrot seed mix (i.e., a mix of millet, hemp, milo, wheat, and canary seed), this may) that is supplemented with fresh chopped greens, soft (cooked) orange to yellow vegetables (e.g., squash, sweet potato, etc.), and pieces of whole grain bread. I recommend mixing in Harrison's High Potency Bird Mash to the seed to help enhance their nutritional value. Additional food treats can include hard boiled egg (shell and all!), cooked beans, sprouted beans, and even small bits of cottage cheese. A shallow dish of calcium should be available at all times. However, some doves pick and choose their favorite foods and tend to eat only seeds so this diet may not provide enough protein, vitamins, and minerals for an egg-laying female or young growing squab (baby doves). For this reason I recommend feeding a diet that is nutritionally complete for doves, such as Kaytee Bay-Mor Dove Mix. This comes in large sizes so you may have to throw out the uneaten food (or use it to stock your outdoor bird feeder) after about 3 to 6 months. Store the unused food in tight containers to it does not get contaminated with flour beetles and other bugs. Make sure it doesn't get wet as it can get moldy and dangerous to eat. Some doves are very hard to switch to an all-pelleted diet but will eat a mix of about 50% seeds and about 50% of a nutritionally complete diet such as the Dove Mix, Harrison's High Potency Parrot Formula (Fine or Superfine sized pellets), or a mash or crumbles for egg-laying chickens (which can be purchased from feed stores. Make sure that you get mash that is not contaminated with insects or mold!) Doves often love the Harrison's Bird Bread and it is a great supplement to offer to doves that eat to seeds.
A bowl dish of water should be available at all times. You may put in a larger dish of water (something like a ceramic pie pan) once a week for bathing. Some doves love being misted with a spray of water several times a week instead of a full bath.
A small dish of grit may or may not be needed. Pelleted diets and mash or crumbles seem to be digested well when doves do not have access to grit. Seeds may need grit but some doves do quite well without grit.