How does one get sprites into a static class?

I have a set of tiles. Each of these tiles has a number attached called the sprite index. When reading these tiles to place them into the world, I take that number and use it to look up a sprite from a scriptable object which holds an array of sprites, called a sprite pallet. I need to access a pallet from the static class that holds the map generation. I also need to be able to set that pallet beforehand and to put sprites in it somehow. I can do one or the other, but not both. I either have a palate I cant use or a sad empty palate that holds no sprites

I have tried making a mono behavior that has an instance variable that is hooked up with get/set into a static class with an array of pallets but It does not show up in the editor, making it rather hard to assign pallets to.

Does anyone know a good way of getting premade, persistent objects, be they scriptable or image-based, into a static class?

I don't know how much the code will help with this question, but here it is, just in case

 [Serializable]
 public class Map 
 {
     //map data
     public int sizeX;
     public int sizeY;
     public int spritePallate;
     public float[,] heightMap;
     public bool[,] walkableMap;
     public int[,] spriteIndexMap;
 }

 public static class MapReader
 {  
   public static Tile[,] GeneratePhysicalMap(Map map)
     {
         DestroyPhysicalMapTiles();
         if (map == null)
         {
             map = new Map(backupMapSize.x, backupMapSize.y);
         }
         tileParent = new GameObject("Tile Parent").transform;
         tiles = new Tile[map.sizeX,map.sizeY];
         Vector2 mapHalfHeight = new Vector2(map.sizeX / 2.5f, map.sizeY / 2.5f);
         for (int x = 0; x < map.sizeX; x++)
         {
             for (int y = 0; y < map.sizeY; y++)
             {
                 Tile tile = map.SetTileProperties(x, y);
 
                 GameObject gameObjectTile = InstantateTileGameObject(mapHalfHeight, tile);
 
                 gameObjectTile.AddComponent<TileBehaviour>().tile = tile;
                 tiles[x, y] = tile;
 
                 gameObjectTile.AddComponent<BoxCollider>().size = new Vector3(1, 1, .2f);
 
                 gameObjectTile.AddComponent<SpriteRenderer>().sprite = GetSpriteFromIndexAndPallete(tile.spriteIndex,/*ERROR*/);
             }
         }
         return tiles;
     }
 
     public static Sprite GetSpriteFromIndexAndPallete(int spriteIndex, SpritePallate spritePallate)
     {
         return spritePallate.sprites[spriteIndex];
     }
 }

 [CreateAssetMenu(fileName = "Pallate", menuName = "SpritePallate", order = 0)]
 public class SpritePallate : ScriptableObject
 {
     public int ID = 0;
     public Sprite[] sprites;
 }