Most of this area of the park is dominated by oaks and this shrubby California sagebrush, also known as Artemisia californica. Fortunately, it's pretty and smells nice and provides a good spot to hide a decent-sized cache. You're looking for a medium lunchbox-type container hidden in one of the shrubby clumps next to the trail.
The Lisa Killough - Cottle loop has one-way, counter-clockwise access for bicycles, which means that you'll have to go the long way to this cache if you're on a bicycle. Hikers can go either direction. The nearest access is from the Rancho San Vicente parking lot, but there are several ways to get here depending on how long you want to hike (or bike).
Calero park hours are 8:00am to sunset. Happy hunting!