Dock, or Rumex spp., has tart edible leaves that are available in the spring, but the real treat to me are the seeds of the dock, which you can find in the later spring through summer in the Bay Area. The seeds can be eaten raw, but are better toasted and, being a member of the buckwheat family, can be used like you would buckwheat (which is a seed itself, not a grain). Try mixing the seeds into a granola or dough for crackers, sprinkling them over poached fish, or grinding them into a flour and using it for baking.
To remove the seeds from the plant, first wash and shake out the dock to dry it then simply run your fingers down the length of the stalk, pulling off seeds as you go. You might want to do this outside, as dock seeds have a tendency to "jump".
Toast the seeds in a cast iron pan on medium high, stirring frequently to cook the seeds evenly. In my experience, 1 cup of seeds in a medium cast iron pan will take about 10 minutes, but this will changed depending on how many seeds you're toasting at once and size of pan (less seeds = more exposure to heat).