What could this be?

[skimel]

Its iron and has a faint simple design on the outside of the cup portion.

 

[ARC]

Bottom part to golf course flag pole... my guess.

 

[tamrock]

Part of an old crank coffee grinder?

 

[bzbadger]

Late 1800's hemorrhoid reducing device

 

[Seek Ye First]

A spinning top??

 

[skimel]

I think it is a cast iron finial possibly from an old bed frame. i think it set cup side down on top of the corner post of a bed?

 

[vhs07]

There's a similar looking brass piece inside some windmill pump cylinders, but being yours is iron, that would rule it out.

 

[Back-of-the-boat]

Could be the spike on the end of a Surveyors tripod leg the metal tip? Or photographers tripod?