Most of the weeds in Southern California are edible. There is an outfit there that will take you on a wild food outing, the climax of the trip is a salad made from weeds. I think this is the proper web link: http://www.christophernyerges.com/index.htm
You do have to be very careful, do not ever eat anything unless someone who knows says it is okay. Certain plants, like ones from the mustard family can be identified by the number of petals. The mushroom societies are good sources of information.
I had a dog that would eat/chew on orange mushrooms from our forest. I asked a local mushroom guide about it, and he said to keep the dog away from them. But I think the dog had his own instincts which he operated safely from. Cows are known to avoid poisonous plants as well.
I would never eat a wild mushroom. Not ever. Here in the Pacific Northwest, there is quite a bunch of folks who do collect them. They even sometimes end up shooting at each other over some of the more exotic kinds!
But every year you hear about somebodies liver getting turned to goo.
I had a contract on a cow for a bull calf to a stud. I went out to feed them before I went to the breed convention. I would be gone a week and I wanted to warn them that my husband, who hated them all, would be feeding them.
We had purchased some hay that had been interplanted with comfrey, supposedly a good plant. But when interplanted, the comfrey cured at a totally different rate than the alfalfa. The comfrey was still very wet when the alfalfa was ready to bale. So he baled it anyway and all the comfrey molded.
I saw that as I was feeding this very nice cow named Tippy. She dove into it as I was also under the impression that a cow would know a good thing from a bad one.
Well there is one bad one that they do not know. And here it was. She was cold and stiff when he went out to get them that night after he put me on the plane.
Entertoxemia C and D from mold.
They didn't tell me until I got home. I was glad for that.