Can I Keep Him? by Steven Kellogg*

While a busy mother tries to accomplish her many chores, her son continually interrupts with a different animal he supposedly finds and asks to keep it.  The mother replies with some reason why not.  With each new animal, he addresses her previous excuses.
The ending is very cute and sweet.
*Highly recommend.
-Borrowed from the library.
Mentor text-persuasive/opinion writing