So it must be something about guys and the backs of their shirts. Boyfriend has a polo shirt where he mysteriously tore a hole horizontally through the white stripe near the collar in the back. The tag is fabric and sewn in totally in a large rectangle, so it wasn't that. So mending #2 was just using white thread and sewing the raw edges back together. Luckily the polo is a knit so I didn't have to deal with any unraveling.
Gütermann thread was 40% off. So I picked up some invisible thread too. Bonus. I'll get to that when I have a chance. Work is crazy right now.