public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            List<MyStruct> list1 = new List<MyStruct>();
            MyStruct myStruct1;
            
            for (int i = 0; i < 10; i++)
            {
                myStruct1 = new MyStruct();
                myStruct1.DysplayMember = "Text " + i.ToString();
                myStruct1.ValueMember = "Value " + i.ToString();
                list1.Add(myStruct1);
            }

            dataGridView1.DataSource = list1;

            comboBox1.DataSource = dataGridView1.DataSource;
            comboBox1.ValueMember = "ValueMember";
            comboBox1.DisplayMember = "DisplayMember";
        }
        /// <summary>
        /// Отображаем текст
        /// </summary>
        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show((comboBox1.SelectedItem as MyStruct).DysplayMember);
        }
        /// <summary>
        /// Отображаем значение
        /// </summary>
        private void button2_Click(object sender, EventArgs e)
        {
            //так
            MessageBox.Show((comboBox1.SelectedItem as MyStruct).ValueMember);
            //или так
            MessageBox.Show(comboBox1.SelectedValue.ToString());
        }
    }

    public class MyStruct
    {
        public string DysplayMember
        {
            get;
            set;
        }

        public string ValueMember
        {
            get;
            set;
        }
    }