Monday, 16th. This morning there was an abundance of water in the little stream and it was running briskly when we left it. If the water was not supplied by the melting of the snow in the mountains, it was really an interesting spring; found an abundance of choke cherries, very large and exquisitely delicious, better than any I ever eat before. Distance traveled, 12 miles.
They had noticed the water in the stream dry up the day before, and then start again during the night. It doesn’t look like Bidwell ever found the answer to this puzzle.
Notice that he says “better than I ever eat before,” rather than ate. He probably pronounced it et, and we now usually pronounce it and spell it ate, although et is still heard in some regions. Compare these present and past tense spellings to read/read. The old spelling of past tense eat can be found in Shakespeare, Boswell, and many other authors.
Chokecherries are best eaten when they are dark red, almost black. To me they look like the berries on pokeweed, a common weed around here, but those are poisonous.
goldfields 
Pokeweed isn’t poisonous but the results from eating it are extremely unpleasant. The berries might be useful as ink but they are dangerous also. The seeds might be toxic if you chewed them. The very young leaves from freshly sprouted plants can be eaten, like spinach, after cooking (a change of water would be wise). A very common free food source in the southern States. Eating any other part of the plant will produce violent and long lasting expulsions – from every place anything can be expelled. But it won’t kill you or cause any lasting effects.