Butternut (Juglans Cinerea) is the most cold-hardy of all walnuts. Uncommon in the landscape compared to Black Walnut or English Walnut, they are worth growing for that reason alone. Produces large, football shaped nuts and valuable timber. Excellent survivability if you're pushing the limits of growing walnuts in your area.
These are 1 to 3 foot bare root Butternut seedlings.
Photo Credit: Nekrasov.ig, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons