This English custom relates tightly to courtship. It was the habit of young ladies to celebrate The May (May Day, May 1) by going out in the early morning to gather garlands of flowers to decorate their families' homes. The young ladies were generally accompanied by young men, and the activities of young people on a (presumably) sunny and warm spring day may easily be guessed.
Herrick's masterpiece is a courting song. The pattern of the holiday was a simple one: courtship, bed, and wed. That is, the young lady went out with her boyfriend to pick flowers. They laughed, played, and courted. Then, in some secluded spot in the fields, they likely consmated their affair. At the end of their activities they would return home and announce their engagement -- with the wedding generally taking place before too many months had passed and before the young lady's condition was too visible (though the customs of the time were properly served so long as the wedding preceded the birth).
If the young man fled, joined the army, or otherwise evaded his obligation to marry, the young lady would find it necessary to pay an extended visit to some relative in another village, where she might well claim that her husband died "so soon after the marriage." Rural girls who bore children without benefit of marriage were thus termed "grass widows," women who became "widows" by lying on the grass [lying with a man out in the fields].
The Maying custom thus provoked scandal among some portions of the citizenry. Ronald Hutton (The Stations of the Sun) notes how Edmund Spenser evoked the beauty of the scene ("Youth's folks now flocken in everywhere / To gather May baskets and smelling brere ...") before condemning Maying as self-indulgence and idleness. Hutton notes a story from one Christopher Fetherston, who spoke of "ten maidens who went to set May, and nine of them came home with child." A Philip Stubbes spoke of around a hundred celebrants of whom "scarcely the third part of them returned home again undefiled."
A popular song celebrating the occasion, "A Pleasant Countrey Maying Song," frankly alluded to the sexual activity:
"Thus the Robin and the Thrush,
Musicke make in every bush.
While they cham their pretty notes
Young men hurle up maidens cotes."
Herrick provides sexual hints throughout his "Corinna's Gone A-Maying," but also alludes to the intention of the young couples to marry (an intention that was no doubt carried through in a goodly portion of these May Day courtships). Bed likely preceded wed in nearly every marriage of the period that was not an arranged marriage. And, as we note the many Elizabethan marriages which were arranged marriages, and further note how many Elizabethan love poems were to mistresses rather than to potential mates, we still find a fascination with romantic love in the culture and find evidence, such as Herrick's poem, that young Elizabethan ladies did marry for love -- at least some of the time.