Several decades ago, we were three days from the trailhead with no food. Let's not get into why that happened, please. It is too embarrassing.
We had to slog through snow for two days, but on the third day we walked into spring greenery. Everything looked delicious, but we didn't know what was OK to eat, so we ate nothing until we got to civilization late on the third day.
Is there a field guide (that doesn't weigh much) to edible plants? Ideally, the guide would come in multiple volumes (although volumes makes it sound heavy!) that cover particular areas. For example, there might be a guide to edible plants in the Sierra Nevada, another one for the Rockies, and so on. What level of specificity makes sense?
Our experience was before on-line anything, but even now on-line would not be much help because most interesting places have no cell-phone reception