Do chicks need something in their brooder to stimulate them?

I have 4 two week old chicks that are fond of pecking the ground and scraping it, and sleeping. Sometimes they will have the odd noise making break, but should I put something into the brooder with them? For example I was thinking of putting an old broom handle sawn off, in with them to perch on, but a quick search on duckduckgo suggests maybe to put in a branch and possibly a mirror and a small pile of dirt from the garden...

I am a little confused, as I thought that those sort of things (not including the mirror) might carry harmful things for them, do I need to clean the branches first? - I don't even want to ask about the garden dirt...

Can I throw a branch in with 2 week old chicks, or do I need to clean it first - and how? Or am I possibly over thinking that I need to much more careful than I actually need to be.