One person's junk is anothers treasure.
 
Old inner tubes with holes in them.
These are very useful for tying small trees to stakes.
 
They can also be used as an emergency repair to a burst pipe. Cut the tube near the valve, then wrap it as tightly as possible round the pipe, overlapping the split by about 10cm each side.
 
Cardboard boxes.
Often we have lots of these, some big, some small. Just ask and you can have them. They have many uses. We like to keep one about the place for any visiting small children to play in.
 
Advice.
You might not like it, but if you ask you'll get it. Advice given early in the morning is less likely to be grumpy than at the end of a hard day.
 
Worn out bits.
These usually go in the bin or scrap pile. We have a regular supply of old wheels and rims that artists like to make into sculptures.  We supplied some to the Transport Museum for childrens workshops.
 
Old rims can be used for making tube shaped things, like this planter. It is best to use alloy rims for this, as the chromium peeling off old steel rims could contaminate the soil.