I haven't actually found anything that rodents dont eat.
They did avoid the menthol crystals I disolved in olive oil. Maybe a couple took a lick and died later so the rest knew to avoid it. Doesn't take much menthol to kill. I labeled the bag of crystals as poison just so hubby wouldn't think they would be neat to taste. People do that and end up in the hospital.
They eat mint stuff.
If you don't want to put down poison there are a few options.
Put out some MouseX. It's not toxic. The corn gluten meal in it is the active ingredient. RatX and MouseX are safe for birds, dogs, and cats if ingested.
Can also mix up baking soda with peanut butter. It takes several feedings and is kind of nasty death for rodents as they can't burp up the CO2 from the baking soda so they bloat until they die.