Walking through the woods near the Pere Marquette river, we saw lots of these colorful little flowers. At the time, none of us recognized them, but I found them pretty easily in a fieldguide. Polygala paucifolia are commonly known as the fringed polygala, gaywing milkwort, or flowering wintergreen.
I teach economics at Kalamazoo College. My wife is also an economist. We were on sabbatical in Europe for the 2014-15 academic year. (Salamanca, Spain, followed by Oxford, UK.) We were in Uruguay for the 2006-7 academic year.