Whether the occasion is a costume party or Halloween trick-or-treating, there are a variety of ideas that can be used to dress a child like a backwoods hillbilly. In fact, you can probably find many of the items you'll need around the house, such as hats stored in boxes or old clothes stuffed at the back of a closet.
Teeth and Makeup
To really create the hillbilly look, a little makeup goes a long way. For example, use a red or orange makeup pen to create large freckles on your child's cheeks. Use a black makeup pen to create small dots on his face to replicate the unshaven look of razor stubble. To complete the illusion, purchase a set of "hillbilly teeth" which can be found in joke shops and costume shops. This fits over the upper teeth, creating the illusion your young hillbilly's mouth is a dental disaster, full of oversize, misshapen teeth.
A number of different types of hats can be used, depending on what you can find around the house. For example, a straw cowboy hat can be crumpled and frayed, while a felt fedora can likewise be beaten up so it takes on a distressed look; you may even want to cut some holes in it. Another option is to find a trucker-style baseball cap, preferably adorned with the logo of a tractor manufacturer of beer company.
A plain white T-shirt can be ripped up a bit, and possibly made to look dirty with a black makeup pen or some charcoal. A shirt featuring a hillbilly-style product logo that can also work. Other options include plaid shirts of varying colors; heavier, warmer shirts may be suitable if your child will be wearing the costume while trick-or-treating on a cold Halloween night. For added effect, stick a small pillow or some type of padding under your child's shirt to create the illusion of a pot belly.
An old pair of overalls can make a great addition to the costume. Size isn't an issue, within reason, as the pant legs can be rolled up and baggy overalls will add to the overall look. A pair of jeans, preferably a bit torn and ripped, will also work; try to use old, worn jeans, and fray the bottom of the pants legs with a pair of scissors. Complete the look by using a length of tattered old rope as a belt.