My dog gets into the yard mushrooms this time of year and it's caused problems in the past. No sodium chicken broth is something my dog rarely turns down but she's a lab, so if she's not eating, it's usually hospital time... Activated charcoal is something the vet might try and you can source it way cheaper on the net.
Our last emergency visit was for what looked like an old mouse-pad ball? I never saw her eat it and had never seen it before. It was round and very hard. It wouldn't pass or puke, so they had to go get it.