It’s the Great Pumpkin, Charlie Brown (1966)

Storyline

This classic "Peanuts" tale focuses on the thumb-sucking, blanket-holding Linus, and his touching faith in the "Great Pumpkin." When Linus discovers that no one else believes in the creature, he sets out to prove that the Pumpkin's no myth—by spending the night alone in a pumpkin patch.