rice. "Hours are green as weeds, and old people are full of gold jewelry. Jewelry is cherished by everyone, and no one in the world does not rely on it. According to the riddle, this thing has two States: first ripe, thinking that hours are like grass; According to the fact that no one in the world can rely on it, it can be associated with food, and according to "the old man is covered in gold jewelry", it can be inferred that it is rice. When the rice is ripe, it will be hung by the head hung by the full grain of rice, so the old man's head is full of gold jewelry. This kind of jewelry refers to food, which everyone needs to eat, so it is very precious. No one in the world does not depend on food to survive. Therefore, when I was young, I was green as a weed, and when I was old, I was covered with gold jewelry. Everyone cherishes jewelry, and everyone in the world is rice.