What part of CA are you in?
I used to hunt yards all the time, when I first got into this hobby in the mid to late 1970s. I would just knock on the door, and say something like "Hi, I was wondering if I could check your yard with my detector, to look for any knick-knacks?"). I almost ALWAYS got a yes. But that was when I was an innocent looking high-school nerdy kid. As the years passed, I started to get more "no's". Not sure if that's d/t the increasingly litigical society we live in, or that I'm older and more ugly/suspicious looking now
In any case, I've moved away from yards anyhow, and gone to strictly old-town urban demo's, mission era adobe sites, etc... so I rarely do yards anymore.
My gut feeling now is, that if you are to be successful in getting access to a private yards, is to find a way NOT to have to knock on the door. Like, drive around till you find someone doing yard-work, or sitting on their porch, etc... The reason is: that the minute you knock on their door, it's like an invasion of their privacy. And you know how jaded society is nowadays to "sales-people". You'll only be thrown into that category, and... no matter what it is you're saying, the rehearsed answer will always be "no". But if you catch them when they're outside, to start the conversation, you're more likely to be on the less invasive side.
One friend of mine even would do this: He'd get the newspaper, and look to see all the garage-sales that were going on in older parts of town. He'd plot them all out in a route, and then go to them, one by one (w/no real intention of buying anything). He'd browse awhile, make small talk, and then comment on the nostalgic beauty of their older victorian home, etc... Then he'd get around to asking "would you mind if I checked the yard with my metal detector, which I happen to have in my trunk with me?". He was very successful at finding willing persons that way. Once again, it gets the homeowner on a sort of more public venue, rather than them coming to the door and talking to a total stranger, interupting their TV show, etc...
Monty
