Filamentosa is basically trunkless. If you want the look of a trunked yucca in your yard you could try Yucca recurvifolia or possibly Yucca rostrata. In your climate they would probably require some protection such as a south facing wall. A raised, gravely bed would also increase your chances of survival. Go to the Plant Delights Nursery web site and look at their yucca offerings.

For the record, I've now grown all but agave harvardiana outside year round and they have all survived as long as you keep them dry in the winter. I cover them with clear plastic containers that have holes drilled in them to keep the air flowing to release humidity.

I live in NW Arkansas but will be driving down to Dallas for work in a couple weeks. Several trunking yucca rostratas and thompsonianas in my area, but no garden centers/nurseries stock them. Wondering if there are any garden centers or nurseries in or around Dallas that carry them, specifically the area between Plano and Frisco. Thank you.

Most likely multiple plants. Recently I have seen stores are getting various kinds Ficus and most are multiple rooted cuttings in a single pot. I guess they look fuller that way and perhaps more attractive to customers. For a multiple trunk tree the individual trunks will be very close to each other at the soil line.