Here is the definitive answer to your question: do they sell stamps at Walmart? Almost all Walmart stores across the country sell stamps. It is quite unlikely a particular Walmart store will not have stamps, unless they have run out of the stock and it is yet to be replenished. Walmart has a nationwide presence. Most Walmart stores are open twenty four hours a day and seven days a week. You can practically buy stamps at Walmart on any day and at any given point in time.
The best part about shopping for stamps at Walmart is the availability of all other essentials you would need. Unless you are buying stamps to collect them or for some non-postage purpose, you would need envelopes and perhaps packaging materials. You can get all of these and more under the same roof. You can walk in with a list and walk out with everything you need. You can use the online store locator of Walmart on its official website to find the nearest location if you are not aware of it already. You may also check with the customer support of Walmart to know for certain if the location you have chosen has stamps in stock. The executive should tell you if the store does not sell stamps.
You may also buy stamps at Walmart online. You can check out the postage stamps section on the online store. There are hundreds of pages of inventory so you can easily find exactly what you need. Just to give you an idea, you can buy postage stamps sporting the stars and stripes, seashells, planets, vintage tulips, ferns, penguins, national parks, pets, patriotic spirals, nativity and sharks among others. You can buy special stamps, ordinary postage stamps, limited edition stamps or commemorative stamps. You can buy forever stamps. You can buy sheets or books of the size you need. You can choose as many strips as you want. You would not be able to buy one stamp, at least among those used in ordinary postage. This is not just a limitation online but also at Walmart stores. You would have to buy a sheet or book. There may be additional charges levied at the store. If you are buying online then you may have to pay a shipping fee unless you have some coupon or you are buying some other items as well that waives the charge on the whole order.