This is the age that you can invent things from home, without spending a heap of $$$.
Nina used to love going through the draws, so I rearranged the bottom draw in the kitchen, and put her favourite toys in their. So that was her draw.
Also arts and crafts were a favourite. They don't care what it is you're using, just go to a discount shop and get some stuff for him. Nina just loved sitting down with me drawing, glueing things, or even doing some sticker books.
This is also a good age to start teaching them ABC and numbers.