With out the tree & its leaves to narrow down. I’m guessing only, maybe it is some thing from the Aesculus genus? According to sources, Aesculus hippocastanum (European horse-chestnut) and Aesculus glara (Ohio Buckeye)are grown in WI. Check it out and see if you have a match. Click on images below to enlarge. If it isn’t in the Aesculus genus, make new post with photo of tree. Best wishes! https://www.google.com/search?q=Aesculus&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjliYbgxLjOAhXC6iYKHaE-Ak8Q7AkITg&biw=1867&bih=909#tbm=isch&tbs=rimg%3ACeAby151sB0IIjiWgb-EUCq6vfhUNZfrqg7r77xlxJJBvpQDM-sz_1l5uMuTt1PiwPG-hxmPtfR-5-2g_1O96IMjs7KCoSCZaBv4RQKrq9ERhR8aoaUBKIKhIJ-FQ1l-uqDusRbW5Lj2ej-_1cqEgnvvGXEkkG-lBGkqCJVWHH9ECoSCQMz6zP-Xm4yERREvXGUH88JKhIJ5O3U-LA8b6ER2eT_1prja8kwqEgnGY-19H7n7aBHKDYLMuQP5ESoSCT873ogyOzsoEYl9UyEBX8w2&q=Aesculus&imgrc=4BvLXnWwHQhC_M%3A