Went looking for Gen Lyon's gravesite recently and finally found it with the aid of a tip and a gps device. He is buried in Natchaug State Forest in Phoenixville in the town of Eastford, CT. The one-acre cemetery is on the side of a hill and appeared, generally, in good shape. In a 1909 state commission report, it was noted that the monument was found on the corner of a small lot in a mass of weeds and bushes. After lengthly negotiations with family members, the lot was increased in size and rearranged to make the monument the central figure.
The monument is sculpted of marble which has not weathered well - the front is mostly white, while the other sides are quite blackened. On the front is a recessed tombstone-shaped die of General Lyon astride a horse. The horse has one leg raised. Lyon, in full-dress military uniform with epaulettes on his frock coat and a sword at his left hip is turned with his bearded face toward the viewer. His right arm is raised high, holding a hat.
Lettering: North, top of base - (the sculpter) Sanford Grasser/Webster, Mass. (little is known of the sculpter or even the date on which the monument was erected , even though some 10-15 thousand people attended Lyon's funeral).
East face - pedestal base, LYON; die, Gen. Nathaniel Lyon/USA
South face - Vera Cruz/Cerro Gordo/Contreras/Cherubusco/Molino Del Ray/Chapultepec & / City of Mexico
West face - Capture of/ Camp Jackson,/ May 10, 1861/Booneville,/ June 16, 1861/ Dug Springs, August 1, 1861.
North face - Born/ July 14, 1818/ Killed in the Battle of/ Wilson's Creek/ August 10, 1861.
About a mile or so from this monument is the birthplace of Gen Lyon. All that remains of this site is a large granite chimney, surrounded by a nicely kept little picnic area.
This site contains the only posted reference to Lyon being the first US General Officer killed in the Civil War.
It puzzles me why these places were relatively difficult to find. Had fun doing it though.