When my late friend Amy gave me this Crinum years ago, she identified it as Crinum rattrayi, which I later learned is a subspecies/variation of C. jagus. However, I believe it must be a different species: the flowers on C. jagus var. rattrayii are pure white, without the faint pink stripe, and the petals aren't as curved.
I'm going to e-mail Marcelle Shephard of Marcelle's Crinums, and see which Crinum she thinks it is. If any of y'all recognize it, though, please let me know!