Start here:
http://dnr.wi.gov/topic/OutdoorRecreation/
You can enter your city and a mileage limit and select "hunting" in the activity section, and it will generate a list of public land sites.
Also here:
http://dnr.wi.gov/topic/lands/
Also, in Wisconsin, there's a fair amount of public land managed by counties. There used to be a mapping system online that would show county land, not sure if it still exists, but I can't find it now. You should be able to get info from local county forestry departments.
By the way, you posted this in the New England forum section -- might get a better response in the Midwest forum.
Good Luck.