This is a very hard question to answer. After all, what is a toy? My four year old has a broken cell phone he plays with- in its current state it is a toy, but if I found it archaeologically, I would pick its original function and not think another thing about it. This is the burden of archaeologists- to prove something was a toy, when to children many everyday objects function as toys, especially those things discarded by adults.

One example of a potential "toy" is the wheeled effigy figures from Vera Cruz. They look like toys to us, but many have argued that they're actually ritual objects. They sure look like toys though. Like this one

Another is this effigy figure from Stonehenge, found with a child's burial.

The easy toys are things we have historical documentation on- dominos, dolls, marbles.

The harder ones are those that we have no proof for- if something is small, is it a toy? And are archaeologists taking children into consideration during their analysis?

Some references: http://www.usu.edu/anthro/childhoodconference/Reading%20Material/New%20Reading%20Material/03Child.pdf