Make the dressing: In a medium saucepan, simmer 1/4 cup water with blackberries. Add California bay laurel leaf and agave nectar. Once the blackberries simmer to bursting, remove bay laurel, and blend to a smooth purée. Set the dressing aside to cool.
Assemble the salad: After washing and drying berries, greens, and flowers, finely chop East Bay pickleweed, and cut gooseberries into halves.
In a salad bowl, combine watercress, pickleweed, purslane, redwood sorrel, piñons, black walnuts, hazelnuts, blackberries, halved gooseberries, and huckleberries, reserving a few of the berries to garnish individual plates.
Pour the prepared dressing and roasted walnut oil over the bowl and toss to combine. Add crushed East Bay salt to taste.
Plate the salad. Top the salad with a garnish of California blackberries, halved gooseberries, California huckleberries, dried California strawberries, toasted piñons, nasturtium flowers, and California violas.
Add a sprinkling of popped amaranth seed and serve.