How to add Texture2D to Popup/Dropdown

I'm working on a Custom Inspector that allows the Designer to select a Color to apply to an Enemy Sprite from a Popup/Dropdown. I can't figure out how to display Texture2D's in the Popup/Dropdown. Text is no problem. Is there a way to do this?

Code:

 [CustomEditor(typeof(EnemySpawnController))]
 public class EnemySpawnController_CustomInspector : Editor
 {
     #region FIELDS
     private const int TEXTURE_WIDTH = 32;
     private const int TEXTURE_HEIGHT = 32;
 
     private bool m_drawDefaultInspector = false;
     private EnemySpawnController m_controller = null;
     private Color m_selectedColor;
     private static List<Color> m_idColors = null;
     private static Dictionary<Color, Texture2D> m_colorSwatches = null;
     #endregion
 
     #region PROPERTIES
 
     private EnemySpawnController Controller
     {
         get
         {
             if (m_controller == null)
             {
                 m_controller = target as EnemySpawnController;
             }
 
             return m_controller;
         }
     }
 
     private static List<Color> Colors
     {
         get
         {
             if (m_idColors == null)
             {
                 m_idColors = EnemySpawnController.ColorTable.Keys.ToList();
             }
 
             return m_idColors;
         }
     }
 
     public static Dictionary<Color, Texture2D> ColorSwatches
     {
         get
         {
             if (m_colorSwatches == null)
             {
                 m_colorSwatches = new Dictionary<Color, Texture2D>();
 
                 foreach (Color color in Colors)
                 {
                     Texture2D texture = new Texture2D(TEXTURE_WIDTH, TEXTURE_HEIGHT);
                     for (int x = 0; x < texture.width; x++)
                     {
                         for (int y = 0; y < texture.height; y++)
                         {
                             texture.SetPixel(x, y, color);
                         }
                     }
                     texture.Apply();
                     m_colorSwatches.Add(color, texture);
                 }
             }
 
             return m_colorSwatches;
         }
     }
 
     #endregion
 
     #region METHODS
     public override void OnInspectorGUI()
     {
         EditorGUILayout.TextField("Enemy Info", EditorStyles.centeredGreyMiniLabel);
 
         if (GUILayout.Button("Select Color"))
         {
             GenericMenu menu = new GenericMenu();
             foreach (Color color in Colors)
             {
                 GUIContent content = new GUIContent(color.ToString(), ColorSwatches[color]);
                 menu.AddItem(content, m_selectedColor == color, OnColorSelected, color);
             }
             menu.ShowAsContext();
         }
 
         m_drawDefaultInspector = EditorGUILayout.Toggle("Draw Default Inspector:", m_drawDefaultInspector);
 
         if (m_drawDefaultInspector)
         {
             EditorGUILayout.LabelField("", GUI.skin.horizontalSlider);
             EditorGUILayout.Space();
             EditorGUILayout.LabelField("Default Inspector", EditorStyles.centeredGreyMiniLabel);
             DrawDefaultInspector();
         }
     }
 
     private void OnColorSelected(object color)
     {
         Controller.SetColor((Color)color);
     }
 
     #endregion
 }