When I have them out on the ground in a tractor I will dig a shallow hole in the grass so they have a place to take dust baths.  If they're in a solid-floored cage I'll take a large plastic plant saucer & fill it with dry dirt/sand for them.  
I also will add sticks or branches for them to have perches, making sure they don't enable the chicks to escape.
I think it's good to give chicks & even chickens some things to add variety & interest to their days, but I don't think they really need "toys" that are for diversion & actual play.  Certainly chicks seem to have "games" like Keep Away, where one will pick up a tasty bit & run around cheeping, but I don't think it's meant as play but as Survival of the Fittest.  
It's when they're kept under close confinement, in artificial conditions, that they seem to need the most diversion.  Otherwise, they start picking & pecking on each other.  Out of their cages/brooders they can usually find enough to occupy their tiny minds.
Something interesting for adult chickens is to tie a head of lettuce, like Romaine, up over their heads high enough so they have to jump up & peck at it.  It certainly provides some entertainment for the people watching them!