Here is one of my "go-to" activities for my toddler on a Rainy (or Snowy day). She's 25 months and has been interested in doing dishes since she was about 16 months old. Lots of "Water Play" is so important for toddlers. (In the video below, she was 23 months old).
I make sure to put in a few different types of brushes, cups (since she loves pouring) and a ladle or two. I try not to put in too many dishes because then she doesn't have as much room to work.
It's been a terrific activity, especially when she has already spent an 1 1/2 hr playing and painting in the bath-tub (I've been trying to be careful about how much bath-time she gets since she started developing very dry skin this Winter).
It's the simple things that bring us so much Joy, right?