Turkey, stuffing, and Cranberry Sauce here
"Note that bread stuffing, sausage, and oysters were popular kinds of stuffing for turkey. Turkeys were typically boiled, roasted, or baked almost exactly like we do today. Turkeys were typically a lot smaller back then, a 10 pound turkey was typical. 20 pound turkeys were reserved for large parties."
In 1864 special meals were provided for the Union soldiers. A picture of Thanksgiving among the Troops appeared in Harper's Weekly magazine.
Thanksgiving was decreed by every president after Lincoln. The date was changed several times, until 1941, when Thanksgiving was finally approved by Congress as a legal holiday on the fourth Thursday in November. President LIncoln's Thanksgiving Proclamation here
And I found this site that I really like-Thanksgiving Civil War Style-since Thanksgiving was not yet an official holiday the foods prepared were not treated as a holiday, this site shows foods common for this time period with recipes here