Themself are all I have — Shell

Themself are all I have-1
Myself a freckled-be-
I thought you'd choose a Velvet Cheek
Or one of Ivory-
Would you-instead of Me?
(F.1054/J.1094)
[1] Themself:: shells, hard outer coverings of some animals, like mollusks.
[2] Myself, a freckled:: her choice is a spotted shell.
[3] you choose:: you will choose a shell with better outlook. Velvet Cheek:: a shell with smooth face.
[5] instead of:: choosing something from the outlook. Shell also means the external part, exterior, or outward aspect (OED shell 24). She considered herself freckled, not the choice of the man, she thought.

The Ivory Shell. The shells belonging to this genus, as originally constituted, consist of two kinds; one, solid smooth shells, spotted with dark red, the animal being spotted like the shell, and covered with an epidermis; the other, smooth, more elongated, and covered with shining enamel. ─ The Student's Natural History (1863)