There is a farm/petting zoo in Romeo off of old Van **** highway. (southern portion of Romeo...) It is west of the new Van **** Highwayaround 30 Mile Road.
The name of it escapes me as of now.
Your kid will love it. They have chickens, goats and many other things to do for kids.
There is also one by Frankenmuth, or more closely, by Bronners. It is a petting zoo. (that one is probably too far out for you...)
I've also included a link for you. It should give you some more leads.
Michigan - pony rides, petting zoos, horseback riding, carriage rides, etc.