Thanks again guys, it means a lot to me that my posts entertain others. 
Now I have swayed a little off course on this one, but I had to have it since I have a collection of tickets and a little medal for this Exhibition.
I would consider it Exonumia, as I have seen wooden rounds much like it, but here is a substantial wooden flat or plaque struck by dies.
It looks a lot like a delicious Hershey's chocolate bar in hand.
My images changed it a bit in appearance.
1876 United States International Centennial Exhibition
Wooden Plaque
MEMORIAL HALL 
This was made available from ADAMS & CO and possibly manufactured at Howell's Marble Building on the corner of 9th & Chestnut Sts. in Philadelphia. They were boxed, although mine is not, and I do believe it is one of a series of five as there were five main buildings on the Exhibition grounds. If I had the box, it would have a label inside like this.

This is pressed or stamped walnut wood and measures 2 5/8 x 3 7/8 and these plaques when found are more often seen chipped or cracked.
I do see a tight small stable hairline crack on mine only on the front, but it doesn't appear to go through to the other side.
I would think this is simply from the aging of the wood. Hopefully at almost 145 years of age, the warping, and shrinking and stressing has run it's course. I will be making a small frame for this and encase it to keep humidity changes minimal.

The Memorial Hall housed beautiful art, paintings and sculptures. President Grant cut the ribbon for the opening of Philadelphia's Memorial Hall on May 10th 1876 to begin the Centennial Exhibition to celebrate the one hundredth anniversary of US independence.
On November 10, 1876, President Grant formally closed the Centennial Exhibition. Admissions totaled nearly 10,000,000 over the six months it was open (159 days), although some portion of the number represents repeat visitors.

An impressive number of admissions, even though there were repeat visitors. The back of this plaque does mention the population of the US to be just 4 times that. Of course it was International, but in 1876 travel was not as convenient as it is today.
The Centennial International Exhibition of 1876, the first official World's Fair in the United States, was held in Philadelphia, Pennsylvania, from May 10 to November 10, 1876, to celebrate the 100th anniversary of the signing of the Declaration of Independence in Philadelphia.
It was held in Fairmount Park along the Schuylkill River on fairgrounds designed by Herman J. Schwarzmann. Nearly 10 million visitors attended the exhibition and thirty-seven countries participated in it.
More than 200 buildings were constructed within the Exposition's grounds, which were surrounded by a fence nearly three miles long.
There were five main buildings in the exhibition. They were the Main Exhibition Building, Memorial Hall, Machinery Hall, Agricultural Hall, and Horticultural Hall.

Visitors could help fund the pedestal for which the Statue of Liberty was to be placed as the "Torch" was on display. For 50 cents one could go up inside.
