Linus will use his blanket to top open the mailbox and mail the letter. Also Linus will try to wait for the Great Pumpkin to show up in the Halloween night and you will need to give Linus’ Blanket to him because he will get cold and got sleep while waiting. So it’s important that you give return it to him.
How to Get Linus’ Blanket
Main Street and you’ll find Linus next to the mailbox. Click on him and he’ll ask where his security blanket is. Now head back to Charlie Brown’s backyard and click on the pile of leaves. Move your cursor around really fast in a circular motion to blow all the leaves out of the way and then click on the blue blanket when it appears. Take the blanket back to Linus and he’ll use it top open the mailbox and mail the letter.