I hope that I can describe this correctly. I just did some "horse trading" at a rendezvous last weekend with a friend for a knife and sheath.

Except for being about 2 1/2 inches shorter, the knife is pretty close to the one Jim Bowie used at the Battle of San Jacinto in 1836 during the Texas Revolution. It's fake of course with a stainless blade but it fit my hand well and will be used for non-period chores.

My question is about the sheath, It's also cheap but to the untrained eye it looks "pretty". It has, for no other word that I can think of, a button on the back rather than a belt loop or other such things. Is this for a Frog? or is it for something else?

Sounds like a good description of a frog to me....

That is called a locket, frog button, or throat button, and maybe a few other names. A frog is the leather collar like sheath that the scabbard slips into, and is retained by the locket via a slit, button type hole or sometimes a small strap on the frog.
I did not know that Jim Bowie lived to fight at the San Jacinto battle.

Thanks WBE. You had a much better description of a frog than I did but we were both thinking the same thing.

As for the accuracy of the 1836 date. I have to admit that I took it from the magazine that referenced the knife and the date without checking it myself. Yes it would have been a "ghostly" trick for Bowie to have been there a month AFTER the Alamo fell.