I've found another poem, The Consumptive's Request, published in 1861 by "Maud Irving" in one of the periodicals that Van Namee often published in. This one is different however, in that the words of this poem show marked similarity to some of the lyrics of I'll Twine Mid the Ringlets, speaking of pale lilies and fair roses. Furthermore, the metre and structure of this poem are almost identical to that of the song, so much so that the poem itself could be quite readily sung to the tune of the song. You can see the poem at this link.

This makes me feel more secure in the conclusion that I've found the correct Maud Irving.