Can anyone tell me what this item is? The description of it that I was sent is below.

"While completing restoration work on an old (c. 1798) over-shot water powered grist mill in Graves Mill (Madison County, VA), a hand forged "unknown" tool was found in a crevice of the stone foundation wall. Attached to this email, are three photographs of said tool with the hopes of you identifying the purpose of this tool? What it was used (it's purpose) for, etc? It is believed to have been a tool used for some type of wood working process (a guess). The 4th photograph is a photo of the wall of the mill that it was found within.
Each of the two prongs are beveled and semi-shaped and oppose each other."

It looks like one of those spikes inserted into stone and brick walls to hang or attach things.

Mortar joint tool?

May be a "Shim", or a "Stay" used in the Construction.? If it is, there will be more in the Walls. Just My 2 cent WAG.