Hey, Ziggy from White Clay here. Yes, the Walmart check thing is a total scam; these criminals are just using the name of our company to make their scam LOOK legitimate. DO NOT DEPOSIT THE CHECK; DO NOT ACCEPT THE ASSIGNMENT.
Once you deposit the check, they'll have you buy a $400 gift card from Walmart (maybe for iTunes or something), scratch it off, then send them digital photos of the card's number. They immediately spend the money on the card; a few days later the check they sent you bounces and you're out $400.
At this point, I have 15 images of the same check and packaging, so no need to send.
But I'm VERY interested in how they reached you. Some people have been approached via LinkedIn accounts, and if you have any screen grabs of that occurring, I can use that to have LinkedIn shut down those accounts.
Or if you clicked on some sort of advertisement on a website, if you happen to have a picture of that ad, we can send it to the site where you saw it and get it pulled to prevent others from being scammed.
Be safe!