Add mushrooms to drippings in skillet. Increase heat to medium-high; cook 4 to 6 minutes, stirring occasionally, until lightly browned. Add shallots to skillet and cook 2 to 4 minutes, stirring frequently, until shallots are softened and mushrooms are browned. Add rice and salt and cook about 2 minutes, stirring frequently, until rice becomes opaque. Add wine; cook and stir until most of the liquid is absorbed. Transfer to slow cooker.