Note: Walmart has recently ended in-store ad match for over 800 select stores. If your store is affected by this change, try using the Walmart Savings Catcher app.
Savings Catcher is a great new tool that automatically compares prices with local competitors. If a lower price is found, Walmart will give you the difference. Just enter your receipt number online or snap a pic of it in the app and you'll receive your cash back on a Walmart gift card for future shopping trips.