Found the code printed on a paper coupon that came in the mail today.
The code printed is ILBOGO18. Works just fine IN THE APP. Log in OR guest. Just tested it. Not valid online. Most likely regional (I am in central IL) so YMMV
the original coupon had an expiration date of 7/26. Today in the mail came a new coupon, same code ILBOGO18 but with an expiration date of 8/30