Books with title Let's Play, Mom!

In this story, Katie the squirrel and Caroline the lemur are together for the first time, playing at the park. Katie finds a treasure while playing in the sand box, it turns out to be a nice, shiny rubber ball that someone left at the park. Katie and Caroline both agree to take it back to the road in front of their home and play with it. They think it's safe because the road is supposed to be blocked from traffic. But little do they realize that Reginald is around and plans to play a trick on them. He removes the barriers that were blocking the road, so cars can come back through again. It takes Katie and Caroline completely by surprise! Will they be Ok? Or will Reginald be sorry he pulled that prank on them? Will they find out it was Reginald who does it? What do they do to him when they do find out? Look and see what happens in the end.