I discovered treasure baskets when Big Critter was about 6 months old. They are boxes, baskets anything really filled with exciting non- toy objects.
This can be scraps of fabric, wooden spoons, pine cones, noisy objects, brushes.
Here’s couple of links for extra ideas:
These are better when child can sit & hold toys unaided however they have benefit from earlier age because parents can aid play.
I love making these & there is so many varieties you can make if I had more room I would definitely make different themes. I would love to see your pictures so get in touch 🙂