Whitetail deer are selective herbivores, focusing on whichever plants are currently the more nutritious. Deer are rather finicky eaters, opting for variety over quantity. Deer eat grasses, ferns, lichens, mushrooms, weeds, aquatic plants, leaves, fruits, grains, nuts, and the twigs and buds of woody plants and saplings.
This young whitetail deer is difficult to see, as it is mostly obscured by the high ferns and saplings, but it is eating these same ferns and saplings, along with some corn and apples that I had left on the ground here a few days ago.