Coupons seem like they would be a major part of grocery gaming, but they really haven't managed to become a significant factor for me. I only end up using coupons a handful of times each year. Coupons come to me in my primary grocery store's weekly flyer and in an envelope and a magazine of coupons in the mail aggregated by a third party company. Newspaper subscribers typically get coupons on Sundays, unless that's changed over the years. I've looked into websites such as coupons.com, but I just do not find enough useful coupons to justify the time it takes to find them.
On these internet sites, which typically require registration with some personal information that they will sell in exchange for giving you access to the coupons, I find many coupons of negligible value for products I don't want. Sugary cereals, heavily processed foods, total junk I don't buy. The coupons provide savings along the lines of $0.75 off if I buy 3. So, not only do shoppers only get about $0.25 off each item, they have to buy three items to get the discount. Lame.
In our modern information age, as newspapers lose readership and grocery stores use membership cards to track shopping patterns and direct incentives, I get good prices for the things I buy due to periodic store discounts without coupons. For example, Dannon Light & Fit yogurt is usually marked as $1.05 for 6oz. That is a crazy price that I will not pay. But for about a week each month the store marks down the price to $0.50 for 6oz. Then I buy 20 of them. When I see coupons for that product, it's remarkable for them to give me $1.00 off for buying two 4-packs. The 4-packs are priced differently than individual cups, and even using the coupon when the 4-packs are on sale rarely brings the price down to $0.50 per cup.
What cognitive phenomena go on when we see coupons? Anchoring is definitely taking place, in which the regular price (artificially inflated) serves as the anchor to which we compare the discounted price so that we feel like we're getting something for a lower price than it's worth even when the discounted price is higher than the product's worth if we stop to really think about it. I think also that the coupons serve as advertisements that cause us to think more about the product than regular advertisements do, and that thinking activates more parts of the brain that contribute to purchasing decisions. It has been found that we get more neurologically excited (dopamine in the anterior cingulate cortex, for example) at the expectation of how satisfying a product will be than when we actually have it. It takes a lot of mindfulness to recognize that you won't really be as happy as you expect you will if you buy a freezer-full of frozen pizzas with a dollar coupon. Off the topic of coupons, this is a contributing factor to obesity as people try to eat until they are as satisfied as they expected they would get.
So, my experiences trying to find a good source of useful coupons have led me to generally avoid such a waste of time. I tend to rely instead on the grocery store's weekly sales.