If you are the patient sort, try Mesagarden.com. They have seeds for Y. elata. It is listed under their "other succulents" catagory There are half gallon Y. elatas at Aridlands.com . cactustore.com has 5 and 7 gal. bare root Y. elata., but I don't know about these guys. I have never ordered from them. They look like a good place.

Here is a link that might be useful: Mesa Gardens

Plants of the Southwest or High Country gardens should have this. Search on the web and good luck. They may have small plants or seed. A call to the cooperative extension office in Las Cruces at NMSU might lead to some sources.

Thanks for taking the time to give me a few places to check.
happy holidays you'all

The key for this species is DEEP pots, minimal root disturbance and limiting soil moisture rot.

The plant above with white sand around it probably has a tap root 6 feet deep. I am not kidding. Good luck. I cannot grow these even here in central NM. Some around town are native and grow from seed. Most that are transplanted die, even here.

I hate to say it but this is a tough yucca for you in TN. Good luck, though.

Yucca filamentosa L.
When I was growning up in TN and AL we erroneously called it "beargrass".
It resembles yours close enough for a rock garden, with prickly pear it might remind you of AZ...