Unknown item

[gibson901]

Can anyone tell me what this item is? I placed an Indian Head penny beside it (found in the same area) to reference it's size.
It looks like some sort of cap and looks to have pieces of concrete in the hole.

 

[A2coins]

Possible drain piece hard to tell

 

[Rookster]

Welcome to Tnet from Mississippi.

 

[firemanphob]

looks like a bung for a metal drum. is it threaded on the outside?