CHICAGO — One rainy day in the spring of 2021, longtime friends Lisa Polk and Kevin Fuller got to talking while shielding themselves from the elements on the 300-level concourse of the Chicago White Sox’s Guaranteed Rate Field. They had met over 20 years ago and became friends as neighboring season ticket holders. Their casual conversation soon turned serious as they started discussing Polk’s health condition — she had a kidney disorder and was about to start dialysis. But she was also looking for a compatible, live donor she could receive a kidney transplant from. Fuller mentioned he, like Po...