It appears at the end of the second line of "To Fortune," which was published in Hesperides in 1648:
Tumble me down, and I will sitLest it be an aberration in the edition I own, I checked it against the new, authoritative two-volume edition of Herrick's work edited by Tom Cain and Ruth Connolly and published by Oxford University Press last year. The emoticon is there.
Upon my ruins, (smiling yet:)
Tear me to tatters, yet I'll be
Patient in my necessity.
Laugh at my scraps of clothes, and shun
Me, as a fear'd infection;
Yet, scare-crow-like, I'll walk as one
Neglecting thy derision.
Herrick's poetry is rich in wit, so it's not entirely out of the bounds of possibility that this is something more than a punctuational oddity. If so, it would predate by more than two centuries the 1862 emoticon discovered in a New York Times transcript of one of Abraham Lincoln's speeches in 2009.
In honor of the discovery of Herrick's invention, we'll close by letting him raise a toast:
"The Coblers Catch"
Come sit we by the fires side;
And roundly drinke we here;
Till that we see our cheeks Ale-dy'd
And noses tann'd with Beere.