Hello Andy,
Congratulations with your new Yucca plants´, they are indeed three very nice specimens.
The variegated plant is however not labeled correctly. This specimen is the very rarely seen Yucca filamentosa var. concava forma albo-variegata. I used to have one my self, but it died after it bloomed in 2011, it was probably too weakened from the flowers and the seedpods on it.
I did make a few hybrids with it:
BMJ 2011-028 Yucca (glauca x flaccida (1819A) X (filamentosa ssp. concava albo-variegata (834)).
BMJ 2011-029 Yucca filamentosa ssp. concava albo-variegata (834) X (glauca x flaccida (1819A)).
BMJ 2011-030 Yucca filamentosa ssp. concava albo-variegata (834) X rupicola, Kerr Co., Texas (388B).
BMJ 2011-031 Yucca filamentosa ssp. concava albo-variegata (834) X (hybrid #500 x glauca (2007A)).
BMJ 2011-035 Yucca (hybrid #500 x glauca (2007A)) X (filamentosa ssp. concava albo-variegata (834)).
BMJ 2011-047 Yucca (hybrid #500 x glauca (2007A)) X (filamentosa ssp. Concava albo-variegata (834)).
The seedlings of the Yucca filamentosa ssp. concava albo-variegata X rupicola hybrid looks very nice, I will have to make some photos of it.
Here you will find some photos of my plant when it was alive:
http://www.bennyskaktus.dk/834.htm
Best wishes
Benny