The Bone Club is a blunt weapon, apparently made from a femur. In the very early game of RUST, it can also double as a gathering tool.
As the bone club is a default blueprint, you can craft one as soon as you spawn on the beach. This is also the only appropriate time to do so.
The bone club is a slightly better weapon than the default Rock. So take the opportunity to rock some sleeping naked on the spawning beach and craft a bone club.
As such the bone club exists only as a necessity for a very brief time within the first few minutes of a wipe.