leatherback
The Treedeemer
This is pretty much how I go about it."Hi, I'm obsessed with miniature trees. Can I take some of your stuff?"
Do note: Difference between private property and company property. When it is company property, make sure you ask for the right person first.
WIth family homes I pick a sensible hour to ring a doorbell. Saturday after breakfast, before lunch is great. Right after dinner not so much, if there are kids...
Dress properly, as if you were going for a BBQ and there will be lots of new people. Casual yet not like you were in the yard for 6 hours. Bring all you need to dig a tree in csae you get a yes, please, go ahead.
Walk up to the door, ring the bell / knock. I tell the owners that I have a silly question, about a plant on their property. Then explain that I would like to dig it. Explain why. And ask them how I could convince them to let me do that.
Most of the time I look at plants that look old. Bare in foliage. Dead sections etcetc. Slipping something in like "Of course I would be happy to get you a young fresh replacement" gets them thinking you are serious.
I find people in general are intrigued by the idea.