We’ve bought a house that has two big-ass black walnut trees that have started doing their thing. I’ve been picking them up as they fall and removing that yellow-green husk and tossing them in a box. Now what? Other than being impressed by the stain one left on my hand when I picked it up with bare hands (I see now why the ink made from this was so common). What are these good for?
Uh, you do know that there are walnuts inside those green, stain-inducing balls that drop from the trees, right? They’re edible you know. Mmmmm… walnuts. Bit of a pain to get out of the husk and shell, of course, but you’ve got edible nuts growing your backyard.
WHAT?! Are you telling me these walnuts are WALNUTS?! 
Uh. Yeah, but do they need to age or cure or anything?
We used to gather them as they fell and put them in the driveway. A few weeks of driving over them would peel off the husks. Don’t do this until the husk has turned brown/black. Take the hard center and crack them open, removing the meat. A nutcracker is sufficient to do this and pretty simple once you figure out how to place it in relation to the split on the nut. A tool that looks like a dental tooth scraper is used to pull the meat out.
Another option, if you would prefer no to deal with the nuts–check into prices of walnut logs. A tall, wide tree with a straight trunk will bring a lot of money. If you have 2 big walnut trees that are in the proper shape, you could easily get a few thousand for them.
Sidle up to them one evening, when they may have been drinking a little too much…complement them on their branches…caress their trunks, but stay away from any knotholes! You don’t want to move too fast. Maybe chase away a few squirrels to show off your manliness.
You need to harvest them soon after falling or while still on the tree, and get the husks off, which is not an easy task. Methods include pounding with a hammer and running over them with a car. The husks stain incredibly.
Your location isn’t listed, so I’m going to assume you’re talking about an Eastern Black Walnut, in which case don’t be surprised if the nutmeat tastes, for lack of a better word, ‘gamy’ compared to store bought (English, I believe) walnuts. Also the shells are substantially thicker and harder, so more work/time will be involved in procuring said nutmeat.
In addition to inks/dyes, the husks contain juglone which inhibits the growth of some other plants and can presumably be diluted and used as a selective organic herbicide. Also, according to an army field manual, you can use it to paralyze fish, which is to say render them immobile (dead? my memory fails) but not toxic for human consumption.
The shell can be ground and used as an abrasive agent (i.e. mediablasting) or added to cosmetic products and soaps as an exfoliant.
Also golf practice, and low-tech laser tag/dodgeball for kids. 
Believe it or not, I’ve met many people in my life who fail to make such connections and/or are totally incapable of recognize food in its natural state. Not that I really thought you were one of them…
The hulls, by the way, make a very nice natural dye for fibers. I’ve used them for wool and cotton.
Black walnuts are very hard to crack. There are special nutcrackers made for them, but they can be expensive. Here is one sold by Hammons Nut Emporium.
Black walnuts are good in ice cream - their strong flavor stand up to the cold. They’re also good in cookies - try them in place of pecans in sandies.
We’ve had a black walnut tree on our family property for well over 60 years.
My grandmother harvested the nuts. Once.
My mother harvested the nuts. Once.
My wife harvested the nuts. Once.
That should tell you something.
It is probably too late, but every year I search out green walnuts and make nocino; green walnut liqueur. You have to get them when you are still able to halve them a knife. If they are at the point where the shell is starting to form, it is too late because they can’t be cut with a knife.
Google “making nocino” and you will see dozens of blog entries on it (and reminds me that I still need to write mine!)
The only contribution I have is the singularly inappropriate line from Clarissa in the Two Fat Ladies that stuck in my head…
Here’s the recipe for their Chicken Breasts with Walnut Aillade.
BTW, here’s a Wikipedia article on Black Walnuts. It features a photo of my wife’s hands, after she harvested the nuts that one time.
Thanks for the ideas, everyone. Nocino, huh? Hm. . .
QtheM-- yeah, I realize this might be the first and last year that I’m intrigued by potentials.
My parents have a black walnut tree. They’re retired, so they hull a few everyday until their done, then just eat them in muffins or oatmeal or whatever. They do taste, um, walnuttier than English walnuts.
One year, Dad set my son and one of his buddies to work on a big bag of nuts. They had a blast going at them with hammers and made pretty short work of them.
Personally, I like to throw them into creeks. They make great projectiles.
Oh, and don’t put walnut tree waste in your compost pile. Your garden will not thank you.
One other problem with harvesting the walnuts that one time: OMG, the squirrels were PISSED!
They depended on those things for the winter food supply, and when a pail of walnuts was set inside the house by the sliding glass door, one particular squirrel tried to bang his way in repeatedly before taking station on a table outside, staring and staring.
This deserves recognition.
Where do you find the barefooted virgin?
Yep, tried them and they’re too far along-- it’s too late here for nocino. Next summer. If I’m not a virgin, do you think it will taste “off”?