dent/field/flour corn types are mostly starch and low on sugar content.

Any of the heirloom sweet corns will be less sweet and more 'Corny' flavored than modern hybrids. Golden Bantam was a favorite befor the modern hybrids.

You can eat field corn in the milk stage and it will not be sweet. At this stage they are called roasting ears.

Concur; Of those with reasonable season probably Truckers Favorite. It is essentially a short season (90 day) field corn that once was used extensively for roasting ears. Golden Bantam is probably the sweetest of the open pollinated corns.