Yes, Q, more probable is amaranthus (the word used in some versions of the song [e.g., The Pale Amaranthus, Shearin, Hubert G.; Combs, Josiah H., A Syllabus Of Kentucky Folk-Songs (1911)]). I just like the sound of amaryllis better, and the flower itself looks nicer than the amaranthus, but you're right about the geographical improbabliity.

Leenia, thanks for your lead about "Mand Irving." Following up on that, I found there are two songs listed as having "words by Mand Irving," one called Broken Harp (held at a library at Brigham Young University), and another called One Fond Heart (held at a Duke University library).

With publication dates of 1860 and 1861, this may well be the same author as the "Maud Irving" of I'll Twine Mid the Ringlets. Since these computer listings often make use of OCR (optical character recognition by computer) it may be that Mand may actually be Maud, since as you've pointed out the one letter can be confused for the other. We can't know until we examine the original sheet music. I've ordered them, will let you know what I find. You many have just located another two Maud Irving songs!