Earlier in the spring, we heard a rustling in our walls and crawlspace. We started inspecting our home, looking for any entrance holes. Sure enough, we found a nest of garbage and insulation behind some stored tiles with a handy path behind our furnace. The rodents had chewed a hole in the back of the container we stored our dog food in. It was entirely covered from view by the container stacked above.
We trapped the area and captured 3 mice. My husband filled any potential holes to inside and we also replaced our dryer vent, which needed it badly. All the noises have stopped so I think we are in the clear until next winter.
There are a number of methods used to get rid of mice without the use of poison or traps. This is a page about using peppermint oil for mice control.