You could be onto something there.Could it be a property boundry marker?
Looks more like a tent spike to me. I may be off though.
BCD
Did you find it near where a railroad is or was? On a side note, we either have the same washing machine or you broke into my house to take that pic.
Correct, used to nail cross timbers to support timbers. Lag screws used also.We used to cross under a wooden railroad trestle to get to some land we were working on. I looked around the old wooden structure and found several spikes just like that. So it's a trestle or bridge spike.