It took me a little too long as a parent to realise that the most engaging toys aren't really toys at all.
One of Miss Pea's favorite 'untoys' is my fabric stash. I have a small basket of mostly large scraps which I display for her to find when we have an 'inside day'.
She recently made a patchwork of our kitchen floor, exploring each piece as she went.
"I am soooo into this!" she enthused.