Field mice are a part of country living, but they don't have to live in your home. Laying out poison is an option, but there is a huge risk of a mouse dying within the walls and causing a huge stink for two weeks. There is also the risk of your favorite pet eating the dead mouse or the poison and subsequently dying.
Control entry points. Field mice can slip through narrow spaces, can jump, and given enough time, chew through about anything. Mice will enter your home through pet doors, through cracks in the foundation, open basement windows, and along pipes. Look for mouse droppings both on the inside and outside of your home for clues to where they enter. You can stuff mouse holes with steel wool, and follow it with spray foam, as mice do not like to chew through either of these substances. You can also cover holes with aluminum or steel netting.
Remove any potential food sources in your home. Put food in closed containers. For example, instead of storing oatmeal in the paper container it came in, store the oatmeal instead in a rigid plastic or glass container with a tight fitting lid. Throw out any food that has evidence of mice damage. Don't leave food or dirty dishes out on counters, as only a little bit of food is enough for a mouse. Make sure to wipe up any spills of food or liquids, and clean out from behind large appliances. Store dog or cat food in a steel trashcan with a lid, and do not put out food for pets except at mealtimes. Store trash in a container with a lid, and take out the trash. Spray for insects and make sure to vacuum up any dead insects as both live and dead insects are potential food sources for mice.
Remove any possible nesting places in your home. Don't leave clothing wadded up in corners, or on the floor. Make sure toys and shoes are not in large piles that could hide a nest. Make sure dressers are rodent-proof. If you can turn the dresser over, or turn the dresser to the rear and see the drawers, it is not rodent-proof. Make sure crafts are put away neatly, and any loose crafting materials are stored in rigid plastic or glass containers with a tight fitting lid. Check behind items stored in closets at least monthly for signs of mice. Try to store linens in a cedar chest or closet as mice do not like cedar.
Remove any food or nesting places outside your home. Tall grass that has seed heads, piles of leaves, stacks of bricks, or even compost piles are great places for mice to live. Termites around your home or even insects and spiders in a crawlspace or basement window wells are also great mice food. Clear out any leaves or weeds against your house and mow your grass often. Locate your garden, cold frames, and compost pile away from the foundation of your home. Finally, make sure that any crawlspaces, window wells, and foundation walls are sprayed for insects, and that termite controls are in place.
Control any mice population that you have in your home. Sticky traps, live traps, or snap traps mouse traps are the best ways to catch mice. Also, the larger metal traps that wind and catch up to twenty mice at a time are the best traps and worth the extra money. If you are a softie and can't stand to see mice killed, you will need to release them from the sticky or live trap at least 1 mile from your home, as it will take no time at all for them to get back in and re-infest your home. If you are not a softie, you can wait until the mice expire, and then remove them according to the manufacturer's instructions. If you do not control or eliminate the mice from your home, you will have another batch of mice within three weeks, as mice reproduce quickly.
County extension agents and pest control companies are other resources that can help you eliminate field mice and point out other things you can do to prevent them getting in your home.