What is that which goes round o’ gars eggs?

Answer. A grindstone. A double entendre is contained in the word egg;
which means either “edge,” or “egg.”

I know a wonderful tree,

The roots stand up and the top is below,

It grows in winter and lessens in summer.

Answer. A glacier.

Four gang, four hang,

Two show the way, two point to the sky,

And one it dangles after.

Answer. Cow with her legs, teats, eyes, horns, and tail.