Posting from the corn capital of the world...

The ears that are primarily yellow with some white kernals are called colloquially "candy corn" though I think that is a specific hybrid. When sweet corn is picked at peak ripeness, typically in July here, the sugars immediately start converting to starch. The fresher it is, the sweeter it is. The way to cook it is to place the ears in a pot of cold water with a splash of lemon juice, heat to boil for one minute, cover and remove from heat. Serbe with butter, salt and pepper.