I just bought an old house in Broadmoor Village/Daly City, CA (right next to San Francisco).
The house is surrounded by very old plantings of Juniper and a few Boxwoods as well. Most have been trimmed as hedges, and they vary in height from about 18" to maybe 42" at the highest. (the tallers ones are more freeform).
I love bonsai, but until now I haven't had any outdoor space to speak of so I haven't actively learned how to collect, shape, and maintain the form. I guess I'm more of an avid admirer at this point...
At any rate, over the next 6-12 months I want to rehab much of the landscaping, including removal of many of these junipers. I was told by the family that lived here before that most or all of these were here when they bought the house in 1958. The house was built in 1939. So I'm guessing these are 50+ years old.
I've only looked briefly, but the trunks on many of these look pretty nice. The smaller hedges have been badly pruned with hedge clippers for decades, so reshaping would certainly be necessary.
I'm offering these up (free, of course) to the Bonsai community. If you would be interested, all I ask is that you let me help you dig up what you like, and teach me a little about how to harvest them. Maybe I'll keep a couple as projects myself (there are plenty for everyone!). A few Boxwood too, but they are much less plentiful.