The singer laments the loss of her thyme. She had spent her life making herself fair, only to find her thyme stolen by a sailor. Now "I gaze on the willow tree," and "I would I were clasped in my lover's arms fast, for 'tis he who has stolen my thyme"
In flower symbolism, thyme stood for virginity. For a catalog of some of the sundry flower symbols, see the notes to "The Broken-Hearted Gardener."
Thyme songs are almost impossible to tell apart, because of course the plot (someone seduces the girl) and the burden (let no man steal your thym) are always identical. For the same reasons, verses float freely between them. So fragmentary versions are almost impossible to classify.
The Digital Tradition has a version, "Rue and Thyme," which seems to have almost all the common elements. Whether it is the ancestor of the various thyme songs, or a gathering together of separate pieces, is not clear to me.
The first line here, "In my garden grew plenty of thyme," is diagnostic but sometimes absent. The thrust of the song is how hard the woman worked to make herself beautiful, only to spoil it by losing her virginity.
To show how difficult all this is, Randolph and Ritchie have texts of this called "Keep Your Garden Clean" which are pretty much the same except for the first verse. On the basis of that distinction, I filed Randolph' with "In My Garden Grew Plenty of Thyme" and Ritchie's with "Garners Gay (Rue; The Sprig of Thyme)."
Many, including Randolph, Ritchie, and Roud, simply lump the whole business as versions of "The Seeds of Love."
Child prints a text (additions and corrections to "The Gardener", p. 258 in Volume V of the Dover edition) which conflates this song, or something similar, with that ballad. - RBW