Really glad to see this thread! I'm trying to decide what to plant and where next spring...mostly for the birds

We only got our girls about 7 weeks ago....long after this year's garden went in, and while lots of what we did plant is suitable for them, I want to increase it a lot next year.
I do a lot of medicinals with herbs and such and had planted 3 patches (about 6 sq ft or so each) of oats in our front yard this spring, and a patch of clover (both are very nutritious for humans as well as critters) The clover is a perennial, so I just lop it off and toss it in the run and they gobble it up! It's hilarious watching them run around with the long stems hanging from their beaks...like a kid with a string of spaghetti. With the oats, I cut off the tops and they snarf up all the seeds. Once the stalks are completely dry, I'll cut them and use them as bedding in the coop. Next year I'll put in a few more patches of them front and back. The plants are really quite attractive when they're scatter sowed in patches like that...rather like ornamental grass. Obviously we don't have enough space to provide more than a very small percentage of feed for the birds, but every little bit helps, and they love it. This fall, I plan to put in a few patches of winter wheat and winter rye as well; come spring it should pop up and I'll do the same thing with it as I did with the oats. I put in a couple comfrey plants this spring too and they've taken off. Guess what? Chickens love it!
Come spring, I'm going to put in some alfalfa...the wonder plant, LOL. It's really nutritious for us and the critters, is a perennial which if cut just after the first flower or two, will come back several times in a season, and is a nitrogen fixer, enriching the soil. When it's ready, we'll just mow it down for the girls. What they don't eat, we'll dry and save for the winter. Besides a patch or two, we'll scatter a few seeds in the back lawn as well...that way the chickens can forage on it. Learned today that they like parsley a lot too, so besides my planter on the kitchen windowsill for cooking, I'll be putting some in the back yard border for them as well.
Gonna put in some sunflowers as well...the regular and some BOSS. I'll have to cover the heads once they start ripening or there won't be any seeds left, but like you, Sally, I'll save the whole head and give it to them in the winter. I'm going to utilize the stalks too...I'll plant runner beans at the base and let them climb the stock. The dried beans keep practically forever and if cooked, the birds love them and it's an extra source of protein for them.
We have portable coop/run which gets moved around to a new spot every 3 or 4 days, so most of the stuff I grow will be cut and tossed in to them..spoiled, or what? LOL. I love the idea of the sprouts, QueenBee but since ours are moved so frequently, I don't think it would work for us. However, I do have plans to sprout stuff indoors for them over the winter so they have some nice fresh treats then too.
I make yogurt and cottage cheese for them, as well as cooked pinto beans (some how I ended up with bags and bags of them) which are all great protein supplements and between that, kitchen trimmings, stuff from the current garden, and weeds, I calculate that since we've had them, we've reduced their intake of commercial feed by 20 to 25%. Not that the feed isn't available to them...it's always there, but they fill up on so much of the other stuff they just don't eat their "full servings" every day. Every little bit helps.
I've been looking for a "safe plant" list but haven't found it

The treat chart does show a lot of stuff that might be helpful:
https://www.backyardchickens.com/a/chicken-treat-chart-the-best-treats-for-backyard-chickens