var PosX = Block.collider.gameObject.transform.position.x;
var PosY = Block.collider.gameObject.transform.position.y + 1;
var PosZ = Block.collider.gameObject.transform.position.z;
var BlockExists = false;
GameObject[] GrassBlocks = GameObject.FindGameObjectsWithTag("Grass");
foreach (var item in GrassBlocks)
{
if (PosX == item.transform.position.x & PosY == item.transform.position.y & PosZ == item.transform.position.z)
{
BlockExists = true;
}
}
if (!BlockExists)
{
Instantiate(Grass, new Vector3(PosX, PosY, PosZ), Quaternion.identity);
}