You can sign-up for a Free Sample of Purina Active Life Dog Food on Walmart’s site.
You’ll have to wait for the screen at that link to load. Underneath the main image, there are three circles, click on the second one to get to the second ad. There will be a free sample link on the dog food there.
Note: There’s a Free Sample Offer for Purina Cat Food on the first circle and a Free Sample Offer for Waggin Train Jerky Tenders Treats on the third. If you haven’t signed up for those yet, you should be able to get 3 free samples!