I meant to post this a few days ago and never did it- but fortunately USPS reminded me today with a nice note in my mailbox.
You can get a free priority mail shipping kit from USPS with 4 Flat Rate Boxes and a gift card envelope.
Hopefully it comes quickly so you can take advantage of the free after rewards shipping services at Office Depot this week!

Last time I ordered this, it never came ;(
You can as well pick up your flat rate shipping boxes and envelopes at any post office. But most of the times flat rate shipping costs are higher than packing stuff into own box. Flat rate priority boxes have price of box included in price of postage.
Flat rate boxes and envelopes would be great if combined with Office Depot promo where you can get 100% in store credit until 11/20 (max 2 shippments a day and max $100 in store credit).
I have tried to order this twice and not gotten it either time ๐ But I do love the flat rate boxes. If I’m going to ship something priority, and especially if it’s something heavy, then it’s always a good deal for me. If i’m not worried about speed then I don’t worry about priority and then do usually save some money over the flat rates.
I ordered these last year and received them, but when I went to use them at the post office I was still charged for the box although they were mailed to me for free. If that’s the case, you can easily pick them up at the post office when you need them.
I love using these flat rate boxes because I am able to pay and print the postage label from home and schedule a free pick up through the website with my mail carrier http://www.usps.com. No lines or trips to the post office. Worth the extra cost of postage for this reason.