You can phrase this in two different ways. Since it uses 좋다, you have to have wolves as the subject and mom as the topic. The other way, using wolves as the object, would require the verb 좋아하다.

건일은 은이 좋아 / 건일은 은을 좋아해 - Geon-il likes silver. Both ways mean the same thing. Literally however, the first way means "As for Geon-il, silver is good."