Foraging for feed and bedding for chicken run in Spain

Hi,

I'm in Cubelles, up the mountain about 5km from the coast (Annual temperature range about 5-29 degrees C). We're going to pick up four Cream Legbar chickens in about ten days and I'm brainstorming local vegetation resources for them. Can you tell me which readily-available grasses are good and what you prefer for chicken run deep litter?

They'll have a roofed, enclosed run with deep litter potential, currently about 10cm of dried pine needles and chopped (by me) dried grasses to cover the hardware mesh predator-proofing on their floor. I'd like to avoid buying lots of bedding if possible. I could probably get some chopped straw from the co-op one town north, but I don't think it'll be organic or cheap. I'm from the American Pacific Northwest where I would forage with confidence, but I've been reading conflicting posts and getting AI advice I'm uncertain about when I take a photo and ask it 'Identify, good for chickens? Can I compost it with chickens?' Sorghum, for example is either a source of cyanide poisoning or the seed heads are a fantastic treat? Pellitory - good to feed or an asthma risk? There's lots of warning about seed heads that could block chickens' crops and suggestions about 'confetti-sized' pieces of grass when offered. Is this an over-the-top warning? I don't remember having this problem with my dad's chickens, but they mostly picked their own, which I won't be able to do here apart from starting some clover for them. (We're in a suburban development with some yard, but unfortunately my in-laws have paved or rocked over a lot of the property.  I do have an upper terrace where I'm starting an orchard but it's full of boix, rough bind weed and other plants that I get 'toxic' answers about. There's also at least one resident owl, who I hear eating the neighborhood's many ferral kittens, so they'll probably be fully enclosed on a lower terrace.)

I've also started a compost ring full of locally scavenged greens and browns in the hopes of boosting the bug population (isopods, beetles,etc.) , I'll have lots of brown hackberry leaves before long, but mostly it's green that's available now, wild asparagus, passion fruit vine, torpedo grass stems, rosebush trimmings, etc. and some banana peels. Out walking (armed with clippers and scissors) I've found fennel, purslane, amaranth, lambs quarter, malva and fat hen, but it's generally harvestable near parking lots or roadside, where it's likely to be somewhat contaminated. Take it anyway?

I'm going to try to grow a patch of perennial kale, but honestly I haven't had great results beyond a few tomato plants and onions since we moved here. A few snow peas and beans, herbs, marigold, calendula and loads of nasturtium. Rodents (rats & squirrels) tend to get my cucumber and squash- and my summer absences usually cost me.

In the olden days I think they used to soak wheat chaff in whey left over from cheesemaking for chicken feed. What do modern Iberians do (besides pay for specialty layer feed!?) Do you know a good guide to Mediterranean grasses?

Thanks in advance,
Eileen