7 and 14 at Lawsonia both fit the bill. The property isn't really a square with corners, but they're both tucked into de facto corners of the property.
One of my favorites on a course that you'll have never heard of is the 13th at Wild Turkey Trace in Lawrenceburg, KY. It's essentially pasture golf on an old piece of farmland with three or four fairly interesting holes and some really awful ones too. The 13th might be the best hole among the 18. It's a 137 yard par 3 that plays to the shallowest green on the course, benched into a steep hillside. No bunkers to give you a chance to spin a recovery close. If you miss long, it's tough to keep the next shot on the green. Miss short and you'll likely have a blind pitch to a tiny target. It's a simple hole that presents about as tough a shot as you can hit with a wedge, and offers some really awkward recoveries. It's the type of hole that could be built on almost any course, but almost no one ever builds one like it.