Not a boulder, but can be found off the somewhat camouflaged trail just off Boulder and Richwood. It's a small container with a log, and just enough room for a few trinkets. Bring your own pen, and be sure to close it up well.
Ng gur onfr bs gur gnyyrfg "cynag" va gur nern. Qba'g trg cbxr'q, zba!