If a stranger picks up your courier on the road and calls you on his own initiative, it is really an act of gratitude. Although the value of the goods is not very high, the behavior of the other party reflects the quality of honesty and kindness.

If you want to express your gratitude, you can consider the following ways:

1. Send a thank-you message or WeChat: You can send a thank-you message or WeChat to express your gratitude and thank the other party for taking the time and energy to contact you.

2. Give a small gift: Consider giving each other a small gift, such as a card, a box of chocolates or a bunch of flowers, to express your gratitude.

3. Invite the other person for a cup of coffee or a meal: If you like, you can invite the other person for a cup of coffee or a meal to express your gratitude and have the opportunity to thank the other person in person.

As for whether to give the other party a red envelope, it depends on your personal thoughts and situation. If you think the other person's behavior deserves some material rewards, then you can consider giving the other person a small red envelope. However, please be careful not to make gratitude too materialistic. The most important thing is to express your gratitude.