(TIN) FOILED AGAIN !

My answer to BOOM's puzzle:- "Invalid Item" 

(TIN) FOILED AGAIN !

A tiny orb that's made of tin,
Well - foil - to be exact.
Has passed between us many times,
Since first the ball was packed.

You put it in my cup of tea,
I put it in your clock.
You flew the coop for brighter lights,
So I hid it in your socks.

You gave it back to me, my son,
Cooked in a chocolate egg.
And I returned it through the post,
From 'Glady Foil', not 'Meg'.

Where is that little ball of tin?
I've not seen for a while.
I'll know when you have passed it back,
By your coy, mischievious smile.