In "To Kill a Mockingbird", who gave Scout the blanket?

While we are not directly told that Boo Radley is responsible for placing the blanket around Scout, we can infer that information from, among other things, Atticus's reply to Scout when she enters the house with the blanket itself.

As Scout is standing in the cool night air outside the scene of Miss Maudie Atkinson's burning house, she fails to notice the person who places the blanket around her. Given her location (just outside the Radley place), we are also led to conclude that Boo is responsible for the act of kindness. This gesture makes the second generous act that we may believe Boo is responsible for. Prior to this event, we are also led to believe that Boo (Arthur) is the party who places trinkets, candy, and treasures in the old tree's knot hole for the Finch kids.