I did a post on this subject on the Old West board a while back:
http://leadadventureforum.com/index.php?topic=71379.0Conclusion: The Ral Partha and the Woodland Scenics O scale deer are the most accurate for White-tailed deer, which are the only deer you would find in the eastern USA. The ears are
way too big

on the Ral Partha deer, and the Woodland Scenics are bare-bones sculpts

which are rather unexciting.
Is there a sculptor in the house? We could use a line of minis covering white-tailed and mule [i.e.western USA] deer, plus buffalo/bison, elk/wapiti, and pronghorn antelope. Not to mention black and grizzly bears.
Here's a painting guide for White-tails:

Note that their coats change colors with the seasons: the buck is in his winter coat, and the doe is in summer colors. Bucks shed their antlers by February and they start regrowing in April/May. Average length of a white-tail is about 71 inches, and height at the shoulder averages 39 inches, although there is wide variation.
Average size compared to a 6-foot man:
