Just a general word of caution. Lowes used to issue coupon codes by email and some other places. They kind of got taken advantage of by people sharing coupons and finding ways to generate their own codes. Couple of years back, they changed their system to thwart some of that. Then they changed no longer issue as many coupons that way and started printing them on register receipts at checkout. You have to present the physical piece of paper, no phone images.
If you've noticed, the list of exclusions on the HF %off coupons keeps growing. You also see the same items at the same coupons prices for months at a time which implies it's just an advertising gimmick and those are more or less the everyday prices. Sometimes the former 'free' items are now on coupon for .99 or so. You also see coupons on that site that never show up in your local emails or printed flyers. That tells me at least some of them are only offered regionally or in other forms of circulation and aren't intended for everyone. I'm sure they know about that site and probably monitor it. They may weigh how much business they get on coupons posted there to see if it works as free advertising to their advantage.
But with their changes to some higher dollar items, I see the potential for changes to their coupons systems and policies. I see a day coming where they may not accept coupon images on phones that aren't somehow tied to the person using them. They keep nagging for your phone number for example and one of the clerks mentioned recently that some coupons may not work if you decline to give them your number. They may be testing such a system and may at some point make it mandatory to provide a phone number in order to pass a coupon image on a phone at all. If they do, it may reject coupons that were not sent to you.
Pure speculation, but considering how other retailers have altered their systems, it may not be too far out there.