It was nearly midnight in late April when Lynell Morris’s husband, Michael, returned home after a shift at work. As he fumbled his keys, the motion-sensing light on their front doorstep flicked on. His eye caught a glint of gold: a .22 bullet on his doormat. It seemed odd as he and Lynell own a different-caliber firearm. Nevertheless, he brought it inside and set it on their kitchen table. A few days later, he remembered to ask Lynell about it. Immediately, she yelped, “Politics!” Neither Lynell nor Michael is running for office. But over the last few months, Lynell had...