WALTHAM — It doesn’t take long for Rasheed Wallace to make an impression.  Ask Paul Pierce, who just one month into the regular season has already heard so many stories and jokes that he could pen a literary masterpiece.

“He’s an extension of Kevin [Garnett],” Pierce said with a laugh after Saturday’s practice. “Between the two you hear a lot of stories. It’s fun. I could write a 400-page book right now.”

Garnett and Wallace are seated next to each other in the Celtics locker room. So it is only fitting that the title of Pierce’s hypothetical book would include both of them.

“I’d keep it simple: Kevin and Sheed,” Pierce said, adding, “[The cover would] probably have them two face to face, smiling.”