You can scale Mt Walkins from the valley, but it is a vertical climb. Here is a photo from Chris McNamara who commented "Tommy starting up the dyno pitch on the South Face of Mt. Watkins, Yosemite Valley. Clouds Rest in the background. Very very snowy for May." Only Gifted climbers should try this. The rest should use the trailhead from Hwy120.
Mirror Lake (in Yosemite Valley) is famous for its reflections of Half Dome and Mount Watkins when the water level is high enough (in spring); it's more a pond than a lake. For more family fun www.thefamilysavvy.com