I am on my way to Staples and also got that email. Will try and then report back, but I'd be amazed if they allowed it. I've never been able to use any of their coupons on GCs.
BTW if you do go to Staples, bring along your old, working smart phones, tablets/laptops and flip phones. Charge them so they start up to get some easy e-cash. Available through the end of October. I believe it is $50 for smartphones, $30 for tablets/laptops and $10 for "feature phones" meaning they must do something besides make and receive calls.
Update:
OK, my Staples was out of bags but gave 20% on everything including clearance items, but they excluded my MCGCs, which, BTW, get you a $20 Staples GC as a rebate if you spend $300.
I bought $1600 in MCGCs in four separate transactions. No one held me to the one per household T&C which appears in the ad.
They also took four VERY old phones. A manager made the mistake of reading aloud "no phone will get under $10" so when they checked their computer list, determining that the phones were worth zero, I said "No, you specifically said 'no phone is worth less than $10." More waiting and checking, which gave me ample time to browse the Hello Kitty clearance items for my great-nieces.
Finally came back and said that it was $10 towards the purchase of a phone. But I was armed with a FatWallet posting that warned me not to be "bullied" into buying a phone; it could be used on anything in the store. In the end the manager gave me two $20 coupons, each good on a purchase of at least $20.
As per usual for super polite PDX, no raised voices were necessary and the customer was always right. So I turned in 4 worthless phones from 8-10 years ago and spent $1660.80, and came away with:
8304 URs
$40 in coupons for Staples
$80 in Staples GCs
$1600 in MCGCs
and a bunch of Hello Kitty gifts for lucky little girls!