That looks like a Spanish Cob coin. The images are similar to others I found with a Google search, it looks to be an early type rather than a pillar type, and later ones are uniformly round. I' sure there are more qualified people on here than me, but that is what it looks like.
The Cob coins were irregular in shape, but the weight is what mattered, and they were hand hammered. they are difficult to positively identify beyond type because much of the time the designs are incomplete.