Edward, Ashley, and Kirby Cash Edward Cash would really rather spend his hard-earned paychecks from the Memphis Police Department on his daughter than on humdrum necessities like student loans, replacing a broken-down car, or saving. “I need money, as much money as I can to take care of this new human in my life,” Cash said about 4-year-old Kirby. Of course, he and his wife, Ashley Cash, a Memphis city planner, pay their bills, in between doting on Kirby. But college loans are different: they get help. The city government pays down $50 a month on each of their loan balances – as it does for some 600 employees. In May, Memphis joined Fortune 500 companies in the vanguard of employers…