There used to be a cache in this park named "Hillside Park Pears III". It was placed in 2002 and archived in 2015. (Don't ask me what happened to numbers I and II, that was before my time.) Not only has the cache been archived, but the park and trails have been improved, In the process the prickly pear cactus that used to adorn the old location has also been removed. However I have found another prickly pear clump in the park and resurrected the Hillside Park Pears name for it.
Park in the upper parking lot and take one of the dirt trails that leads uphill to a paved trail. The prickly pear clump is nearby. The cache is located very near the cactus, but not deep in it. You should be able to retrieve it without getting pricked, at least not badly.