Who gives Wemmick gifts & why?

Clients give Wemmick gifts because they have no money to pay their bills.

“O yes,” he returned, “these are all gifts of that kind. One brings another, you see; that’s the way of it. I always take ’em. They’re curiosities. And they’re property. They may not be worth much, but, after all, they’re property and portable. It don’t signify to you with your brilliant lookout, but as to myself, my guiding-star always is, ‘Get hold of portable property’.”