After chapter 2 begins, you can purchase a Ball, Blocks, and a Wooden Car from Van for your child. Usually you place these in the toybox in your house, but if you instead put them on the shelf in your tool room, you can go back to Van and purchase another one of each. While you can't buy more than one at once, if you continue to buy them one at a time, and put them on your tool room shelf, you can get up to 99 of each, and then buy one last one to put back in the toybox.
This does not work with the Scratchpad.
This trick is useful, as some of the town residents like the toys as gifts.