The oldest public Japanese garden in the country, this Golden Gate park gem is a great place to walk, check out the koi, structures, statues.. or have a cup of tea :)
Many of the world's first fortune cookies were served in this garden by Makoto Hagiwara (preserver of the garden after the "California Midwinter International Exposition" in 1894) who is credited with introducing them in California.
A great way to see the garden is on a SF City Guides tour (schedule). It's 45 minutes long, and the Monday and Wednesday strolls don't require admission :)
Website: http://www.sfpt.org/japanese_tea_garden.html
Wikipedia: http://en.wikipedia.org/wiki/Japanese_Tea_Garden_(San_Francisco,_California)