I found seats departing Los Angeles LAX on Friday, March 15, returning from San Francisco SFO on Sunday, March 17.
This price is available for weekend travel departing on Thursdays or Fridays, returning on Sundays or Mondays, from March through May. Lower fares are available for travel on Tuesdays, Wednesdays, and Saturdays.
Need a room in San Fran? Here's what's available for the mentioned weekend dates on Hotelwatchdog.