Ah, found the old article. It was the
Annals of Improbable Research, not JIR. Here is a
link to a copy.
I misremembered and many of the unwrapped items were blocked by a counter clerk noting that deliveries must be wrapped.
But a $20 bill in a clear envelope was delivered in 4 days.
An unwrapped snow ski with postage and mailing label attached was delivered in 11 days. (Though recipient was warned that packaged must be wrapped)
Closest to a bowling ball: a fresh coconut. Received from Hawaii in 10 days.
An unwrapped street sign - 9 days.
An unwrapped deer tibia - 9 days.