Giant Trillium can be found along the lower part of the Steep Ravine Trail, Mount Tamalpais State Park.
On Hamms Gulch Trail where the trail crosses the creek, next to Alpine Road.
This trail was loaded with wildflowers today. Red trillium, buttercups, milk maids, plus teensy vetch, forgetmenots, miner's lettuce, and chickweed whose blossoms were only about the size of my little fingernail.
Beautiful yellow-flowered Trillium blooming
up close Giant Trillium (Trillium chloropetalum), Leona Canyon Regional Open Space Preserve, Oakland, California
The weird bit is a stray miner's lettuce.