Conversation:

"A friend to the people,
commend me the Yak,
you'll find it's just the thing.
You can milk it or eat it,
or ride on its back,
or lead it about with a string"

Where does this quotation come from, and why is it cluttering up my less than tidy synapses?

Cheerful Dragon answered this question many weeks ago. Look under the conversation entitled "Hilaire Belloc"below. I think both of you have misremebered the first line, but since I have no way of backing this assertion up, won't mention it.