The box comes from Shreve & Co., a jeweler in San Francisco which as been in business since 1852. But that is not the original presentation case which came with the item. The original cases had "Commemorative Medal" on the top in gold gilt letters.
What you have is a commemorative medal. It was produced for the U.S. Centennial Exposition in 1876 in Philadelphia, PA. The following types were made and sold at the exposition:
HK-20 - Silver. 38mm. 10,133 were struck.
HK-21 - Bronze. 13,000 were struck.
HK-22 - Gilt. 10,500 were struck.
HK-22A - White Metal. Only 3 known.
The dies were engraved by William Barber.
Silver was struck in a Mint Exhibit on the exposition grounds, sold for $3
Bronze and Gilt pieces struck at Philadelphia Mint, sold for 50 cents each.
Dies were destroyed when exposition closed.
I think what you have is an HK-20 made of silver, composed of 24.7 grams.
These are rare. So you should definitely hold on to it. But the value I think is somewhere around $150. But I'm no expert.
