If you get an unmarked envelope with a debit card in it, do not throw it away as it could be your stimulus payment from the United States Treasury.
From EPI cards:
Your Economic Impact Payment Card contains the money you are receiving as a result of the Coronavirus Aid, Relief, and Economic Security Act (CARES Act). The EIP Card is sponsored by the Treasury Department’s Bureau of the Fiscal Service as part of the US Debit Card Program.
From the IRS:
Some payments may be sent on a prepaid debit card known as The Economic Impact Payment Card.
The Economic Impact Payment Card is sponsored by the Treasury Department’s Bureau of the Fiscal Service, managed by Money Network Financial, LLC and issued by Treasury’s financial agent, MetaBank®, N.A.
If you receive an Economic Impact Payment Card, it will arrive in a plain envelope from “Money Network Cardholder Services.” The Visa name will appear on the front of the Card; the back of the Card has the name of the issuing bank, MetaBank®, N.A.
Information included with the Card will explain that the card is your Economic Impact Payment Card.