I would recommend looking for dead elms year round and marking them on a mapping tool. Then, when it’s mushroom season you are looking for mushrooms instead of dead elms. Start with the warmest dead elms (south facing/lots of sun), and cover lots of miles. The elms have a shelf life. Once they lose most of their bark and start producing pheasant backs they are pretty much done. I like to go out and find mushrooms, then go get the beginners or kids so they have a good experience. Good luck.