Hamilton Hume opened up the Yass plains for settlement in 1821. After its construction in 1835, Cooma Cottage, not far from Yass, became Hume's home until his death there 1873. Today, Cooma Cottage houses a museum featuring the life of Hume, as well as a gallery of local art.
The cache is in a smallish tupperware container not far from the Cooma Cottage entrance off Yass Valley Road. Access is easy from the road, but the cache is surrounded by long grass.
Cache container may be a little sticky. A pair of gardening gloves or similar wouldn't be a bad idea. :-)