This is the (upside-down) top of a black locust fence post. The wet and muddy post was brought to me, when I gave an American chestnut talk to a county forestry board, by a farmer who thought it may be American chestnut wood.  I brought it home, dried it out and took photos of it illuminated by ultraviolet light to prove to the farmer that it was black locust and not American chestnut.  Black locust glows bright yellow under ultraviolet light; American chestnut does not glow at all.  Black locust wood is also much harder and denser than American chestnut wood, but it is difficult to tell on weathered pieces such as this.  27” x 8” x 5”