PlantExample.cs

class Plant : MonoBehaviour {
  Sprite sprite;
  float growTime;
  AudioClip sfx;
  
  void Start() {
    StartCoroutine(WaitForSeconds(growTime));
  }
  
  IEnumerator WaitForSeconds Grow(float duration) {
    yield return new WaitForSeconds(duration);
    OnFinishedGrowing();
  }
   
  virtual void OnFinishedGrowing() { }
}

class MoneyPlant : Plant {
  double rewardMoney;
  
  override void OnFinishedGrowing() {
    // todo give the player rewardMoney
  }
}

class SeedsPlant : Plant {
  int rewardSeeds;
  
  override void OnFinishedGrowing() {
    // todo give the player rewardSeeds
  }
}

PlantSpawner.cs

class PlantSpawner : MonoBehaviour {
  enum PlantType {
    Carrot, Parsnip, Potatoes
  }

  MoneyPlant moneyPlantPrefab;
  SeedsPlant seedsPlantPrefab;
  
  Sprite carrotSprite;
  Sprite parsnipSprite;
  Sprite potatoesSprite;
  
  void SpawnPlant(PlantType type) {
    Plant plant = null;
    switch (type) {
      case Carrot:
        plant = Instantiate(moneyPlantPrefab);
        plant.sprite = carrotSprite;
        plant.growTime = 10;
        // ... etc.
        break;
      case Parsnip:
        plant = Instantiate(seedsPlantPrefab);
        plant.sprite = parsnipSprite;
        plant.growTime = 5;
        // ... etc.
        break;
      case Potatoes:
        plant = Instantiate(moneyPlantPrefab);
        plant.sprite = potatoesSprite;
        plant.growTime = 30;
        // ... etc.
        break;
    }
  }
}