What are these?

[toscarthearmada]

My father recently purchased new hunting land.  He stumbled across these and didn't know what they were!  They are REALLY large (about the size of a Gatorade bottle lid) and appear to be the cap to something.  Anyone have any idea?

[mauser 98k]

Those would be the tops for the old Pepsi Cola Syrup used in soda fountains.  it used to come in a big bottle separate from the carbonated water....