If you are interested in what medieval children played with, i.e. theirs toys and so on, rather than the things they found lying around and used according to their imagination, then this is an excellent site. It is part of the lars datter site, which offers a great deal of scope and information. The site’s official name is Medieval and Renaissance Material Culture.
My search for information about hobby horses is what took me to the site, and I thought it would be of interest to those who are absorbed in all things medieval.