Magoo's Pizza, 639 Santa Cruz Avenue, Menlo Park, CA

This is a fake poster but the Warlocks debuted at Magoo's Pizza on May 5, 1965.

The Stanford Daily October 30, 1964

In 2012 the address of 639 Santa Cruz Avenue is a furniture store.

5/5/65 Warlocks (first Warlocks performance)
"It was really high that night - but it wasn't folk music, nobody knew what it was - it was intense and alien. We boogied and got off on the Warlocks. Phil stood up on the redwood table and danced - the one and only time I ever saw him dance. Phil's head was reeling..."(3) 

5/12/65 Warlocks
The atmosphere inside Magoo’s was strictly pizza parlor—bright overhead lights, long tables, ovens in the back. The band was set up by the front plate glass window, confined to a rather narrow area without a stage. Jerry Garcia was on the audience’s left, Pigpen on the far right. Those two, especially, looked somewhat menacing (at least to a suburban 15 year-old). They reminded me of outlaw bikers. Bob Weir, Dana Morgan, and Bill Kreutzmann were clean-shaven and looked more like guys you might see in a high school band.

The music was stunning. I have never forgotten it, although I cannot recall the specific set list. I think they did some Stones covers and I know that Pigpen sang “Little Red Rooster.” (2)

5/19/65 Warlocks
I'm not sure if Magoo's was the kind of place where a new band needed a "booking," or if just a chat with the manager would suffice. Garcia remembered, "We said, 'Hey can we play in here on Wednesday night? We won't bother anybody. Just let us set up in the corner.'"
Given the high-school crowd, perhaps it was Weir's circle of friends who suggested Magoo's...(Light Into Ashes)

5/26/65 Warlocks
They played every Wednesday in May. The club was packed with students from Menlo Atherton High School, thanks to shrewd campaigning by the group's first fans. However, despite the promising start to the young band, bassist Dana Morgan was not cutting it. Garcia's friend Phil Lesh saw the last Wednesday night gig (on May 26), and Garcia invited him to replace Morgan (Garcia had to teach Lesh to play bass, as Phil only played trumpet, piano and violin).(1)

In Phil Lesh's book, Searching For The Sound, he says, "Magoo's, unfortunately, had discontinued live music because people just wouldn't stop dancing!"

1.)^Arnold, Corry, Lost Live Dead, 2010-02-06, Summer of 65
2.)^Brown, Philip, Cosmic Trends, Chapter 14, Uranus-Pluto Profile: The Warlocks
3.)^Harrison, Hank, The Dead