Sumo Slammer Boy

From Ben10versepedia

In the beginning of the episode Washington B.C., Ben as Heatblast rescues a boy and his mother from a burning building. The boy is carrying a box full of Sumo Slammers cards, and he has a Gold Sumo Slammer card that Ben has been looking for. Ben asks him were he got it from and the boy replies from a box of Sumo Slammer cereal.