Listing of Trail Loops by Their Starting Point

All three of the listings in the menu above show where to park. (Text in green font.) Here, where to park is how the listing is indexed. That is most appropriate for trails which are loops. (You end up where you parked.)

Amerige Heights Town Center     Emery Park and Sally’s Trail (.9 mi)
Hillcrest Park north parking lot (½ mi north of Brea Blvd.)    Brea Dam Park (1 mi)
Fullerton Sports Complex   Brea Dam (upstream) (1 mi),   Lost Trail (1.2 mi)
Tree Park (Parks Rd, N of Rosecrans)   Nora Kuttner (1 mi),    Rosecrans (1.6 mi)
Acacia Park (where Yorba Linda Blvd ends)     Acacia Park Fullerton Creek  (1.2 mi)
Gilbert and Castlewood       Castlewood Trail (1.1, 1.4 and 3.6 mi)
Rosecrans and Sunny Ridge      Clark Park (1.2 mi),      Castlewood (3.6 mi)
Rolling Hills Drive, east of the the 57      Gilman Park  (1 mi)
Entrada off of Harbor N of Bastanchury     San Juan Park (1.9 mi)
Garden of Eden (Valencia Mesa W of Harbor)    Horse Alley (1.8, 2.5 and 4.4 mi)
Lakeview Drive on Euclid      Laguna Lake Park (¾, 1.2 and 1.9 mi)
Payne Stewart Golf Course Parking Lot       East Coyote Hills Trail  (2.8 mi)
Euclid near Valley View        Hiltscher Park Trail  (2.1 mi)
Valencia Mesa Bridge over Juanita Cooke      Horse Alley  (1.8, 2.2, 2.5 mi)
Summit House Restaurant Parking Lot      Panorama Trail (2.8 mi)
Bastanchury near Malvern     Bastanchury Park (4.4 mi)
Muckenthaler Cultural Center    The Muck Walk (3.2 mi)

Trail Loops that start where there’s a place for a group to gather:

All three trail listings (menu above) are for dirt trails which were developed in the 50s by Fullerton Recreation Riders (horse people). Most people prefer these trails over sidewalks. But to make journeys into “trail loops,” which is what this listing is about, there has to be some walking on sidewalks. That compromise is why your first consideration should not be this listing, but the one on the far right. Going out-and-back along the same path allows the whole trip to be on a dirt trail. In addition, during the “-and-back” part of the walk, you are facing a different direction, so the scenery is completely different.
____Yes, you can going the other way on a loop, which makes for a different journey. Another way to make the same trail different is to go out at a different time of the day. It makes the trail entirely different. Morning vs mid-day vs evening is more different in Southern California than is a change in season.