Scientific name: Brodiaea coronaria
Native American names: Topoderos (Wiyot), Walla (Miwok)
Plant family: Liliaceae
Description: This small perennial herb grows up to 30cm tall and produces a bluish purple flower. Its thin 2-3mm wide, grass-like leaves disappear before the flower six pedaled flower blooms. At the base of the stem a scaly corm sticks out of the ground which stores nutrients and serves reproductive purposes.
Range: Brodiaea coronaria thrives from British Columbia, to the Sierra Nevada Mountains, along the Cascade Range, and throughout northwestern California.1
Habitat: It is found in gravelly prairies, grassy slopes, rocky buffs, valley grassland, foothill woodlands, mixed conifer forests, and volcanic mesas from sea level to 1600 meters.
Historical and Contemporary Uses: The corm of this plant was regularly gathered by Native Americans such as the Wiyot, Atsugewi, Miwok, Yana and other tribes all along the west coast. Natives used wooden digging sticks to unearth the bulb and ate it raw, boiled, or cooked it in pits.
Native Americans would work the land that this plant grew on by 1) consciously breaking off cormlets from the harvested parent corms and replanting them; 2) sparing whole plants; 3) harvesting the corms after plants have gone to seed and dumping the seeds in the hole; 4) burning areas; and 5) irrigation. They would also dig around and thin the corms as well as break off cormlets and replant them. The digging was a form of tilling which stimulated growth and prevented weeds.
S. A. Barrett and E. W. Gifford in 1933 describe the uses of B. coronaria as well as the details of the traditional pit roasting methods:
Walla (B. coronaria)… is dug about the first of May when its shoots are just appearing above ground. The bulb lies deeper in the ground than that of the Mariposa lily. It was dug by both men and women, the occasion being a four-day excursion and picnic. The time for the digging was set by the chief. Four days were spent in digging the bulbs, during which time none was eaten. The bulbs were transported in burden baskets to the cooking place, where they were cooked in the earth oven on the fourth day.
The earth oven for the bulbs consisted of a hole about a foot or foot and a half deep and three feet in diameter, excavated with the digging stick. Stones were heated in a fire built beside the pit. When the fire had burnt down the coals were raked into the pit and the hot stones put on top of them. Over the stones were put the broad leaves of the Wyethia helenioides Nutt. When the stones were completely covered by the leaves, the bulbs were poured into the pit to a depth of about six inches. These bulbs were covered with leaves, on which hot stones were placed. The whole was covered with earth. Then water was poured around the edges of the pit, so that it worked down to the hot stones and coals, thus producing steam for the cooking which lasted about one hour. After cooking, the bulbs were removed by hand and placed in an openwork basket tray (tcamayu, C). Then a second and a third lot were cooked if the quantity gathered was large. Both walla and Mariposa lily bulbs were eaten without salt.
The first European record of this plant was by the Scottish Botanist James Brodie of whom the genus Brodiaea is named. He wrote:
On the Point near the ship where… a few families of Indians live in very mean Huts of Sheds formed of slender Rafters and covered with Mats. Several of the women were digging on the Point [Puget Sound] which excited my curiosity to know what they were digging for and found it to be a little bulbous root of a liliaceous plant which on searching about for the flower of it I discovered to be a new Genus of the Triandia monogina [i.e. Brodiaea]. This root with the young shoots of Rasperrie and a species of Barnacle formed the chief part of their wretched subsistence.
Plants of the Pacific Northwest Coast speculates that the name “harvest brodiaea” comes from its close relationship to B. Hyacinthina, which was more difficult to harvest. Also the flower blooms later in the summer than most lilies.
 S. A. Barrett and E. W. Gifford Miwok Material Culture: Indian Life of the Yosemite Region http://www.yosemite.ca.us/library/miwok_material_culture/bulbs_corms.html