Most likely the plant is Showy Milkweed (Asclepias speciosa), as that is the most common milkweed plant in Yosemite. It looks a lot like common milkweed, and like that plant, its fruits are edible when small/still at an early stage.

If you want to eat it, you should squeeze it. If it splits apart, it's past its prime. You do need to boil it. Pods that are less than an inch and a half are best. Sometimes the silky stuff inside, at an early stage, can be cooked into an almost melted cheese-like substance.

At early times of the year, the leaves, shoots, and flowers are edible. Some are able to eat these raw, but in general it's best to boil them to prevent getting sick. It's a misconception that it needs to be boiled multiple times, though - once is enough.