I originally purchased paper I bonds through payroll deduction when they were first released in 1999. (fedretire.net)
They no longer issue paper bonds except for those who select them as an alternative to receiving a check for their income tax return. (fedretire.net)
The name «coupon» arose because in the past, paper bond certificates were issued which had coupons attached to them, one for each interest payment. (en.wikipedia.org)