I don't know what variety we planted - it was in Gurney's or one of those type seed catalogs, but you could buy one and get the other for a penny. Ours were small bareroot trees upon arrival, but in three years time, I'd guess they were 20 -25 feet tall and bearing.

Hope this helps.

Tom,
I grew up down in Lee Co., AL. The native red mulberry, M.rubra, is quite common there, and I've selected and grafted one M.rubra selection from Lee Co., which I'm now growing up here in KY, due to its heavy production of large, tasty fruits.

Dr. A.J.Bullard, of Mt. Olive NC, the long-time chairman of the NAFEX Southern Mulberry Interest group ranked available(and some not all that readily available) mulberries in this manner, for the Southeast:
M.nigra - generally agreed to be top-quality, but temperature fluctuations, humidity, and fungal leaf & twig problems preclude successfully growing & fruiting it in the Southeast.
M.albaXrubra hybrids - Silk Hope, Sullivan, Illinois Everbearing, Wellington. (In my plantings, IE is the gold standard - large berries, good flavor, bears over a 4-6 week period; Wellington(selected in Geneva NY) is a piece of crap here; I've had no personal experience with Silk Hope or Sullivan, though I've seen good reviews for SH).
M.rubra - (Carlton)English and (Janie)Watts
M.alba - Shangri-La, Pakistan
In his estimation, it's a toss-up between the top M.rubras and M.albas, with the rubras heavier on the acid component of flavor, and the albas not having quite enough acid.

They are fast-growing trees. Most of mine have been purchased as bareroot graftlings, or I've transplanted M.alba seedlings and grafted named varieties onto them. I have purchased a couple of potted varieties from EL, but the bareroots have performed as well or better than the potted ones.
For other potential sources, have a look at the nursery/supplier list at the NAFEX website.

Here is a link that might be useful: NAFEX