James and Betsy Clark of Caddo, Okla., and Lisa Clark of Coppell, Texas, are pleased to announce the engagement and upcoming marriage of their daughter, Krista Elaine Clark to Aaron Houston Walker, son of Jack and Thea Walker of Atoka, Okla. The couple will exchange their vows on April 28, 2012 at 6 pm in the evening, at her family's farm in Caddo, Okla. Friends and family are cordially invited to attend.