Oh dear how unpleasant. I dont think I need to change my behaiour
though do you? Such a situation has never cropped up in my group and
it hasnt caused any problems so far So if it aint broke dont fix it

You can of course do whatever you please when you arrange pick-ups
with people via email or the phone.

However I recall another case on West Norfolk where someone did an
unattended collection - and took the whatever it was the items had
been left in for protection.

The offerer hadn't intended to give the box/whatever away - and the
taker, I believe, said she'd subsequently thrown it away.

There's also a danger that the taker will also take any other items in
or around your greenhouse that they fancy - possibly an item intended
for another freecycler.

I've had one person when picking up, start the "can I have this? can I
have that?", when they see I have a lot of building materials about.

If I wasn't there, I suspect a very few *would* help themselves.