When you file for a change of address at the United States Postal Service (USPS), they provide you with a ton of coupons from retailers like Lowes and even Best Buy. Reddit user drewsaysgoveg discovered that you can get these discounts even when you're not moving by simply pretending that you are.
All you have to do is request a change of address form at the post office for a package full of coupons (and the forms, of course). Alternatively you can find printable coupons by going through the change of address process online. The physical forms come with the downside of actually visiting the post office, and the online forms come with the downside of actually filing a change of address and costing $1. Of course, you can always just file for a change of address with an old one, but obviously getting the physical forms is a lot easier if you have a post office nearby.
LPT: Always save 10% at Lowe's by getting a change of address form from the USPS | Reddit