Can you eat a pigeon egg?

Pigeons are grain eaters. Rice, white or brown, split peas, barley, buckwheat, canary seed, etc., are all good first options to feed a lost bird with.

For racing most fanciers use the 12% mixture of grains.

Yes there is no reason why not. Bird eggs are a common food and one of the most versatile ingredients used in cooking. The most commonly used bird eggs are those from the chicken. Duck and goose eggs, and smaller eggs, such as quail eggs, are occasionally used as a gourmet ingredient, as are the largest bird eggs, from ostriches. Gull eggs are considered a delicacy in England, as well as in some Scandinavian countries, particularly in Norway. In some African countries, guinea fowl eggs are commonly seen in marketplaces.