You're looking for a small cammo'd pill bottle.
You're in the Sierra Pelona Mountains of the Angeles National Forest...and near the site of the St. Francis Dam disaster, which is registered as California Historical Landmark #919. The dam failed on March 12, 1928 and the resulting flood took the lives of at least 431 people (Wikipedia). This beautiful section of road is barricaded and closed to traffic...but will be easy hiking and biking...and you'll probably hear the sounds of wildlife along the streambed...we heard the music of birds and frogs but lots of other wildlife will be found here. Be careful where you poke around...especially during the warm, summer months...use caution because of snakes. Bring some extra batteries, water, and a pen for your hike...and it's always best to hike with friends! As always, leave more than you take...and CITO.