The scion.. What is it:
 
 
Grafting describes any of a number of techniques in which a section of a stem with leaf buds is inserted into the stock of a tree. The upper part of the graft (the scion) becomes the top of the plant, the lower portion (the understock) becomes the root system or part of the trunk. Although grafting usually refers to joining only two plants, it may be a combination of several. A third plant added between two others becomes the trunk or a portion of it. This is called an interstem.

Trading scions would be like trading trees before it grows.  You just need the recipie to create that exact same looking tree etc and what scion(s) where added to create the end result.
Scion wood may be collected during the winter. It should have a diameter of 1/4 to 3/8 inch. If the scions are left on the tree until spring, there is some danger that the buds will start to grow or be injured during winter. Basically the scion has to be dorment!  
Store in a cold, moist place at temperatures close to 34 degrees F. At home, a few scions could be stored in a plastic bag in the refrigerator with moist paper towels. Do not store in a freezer.
 
Regards,
George T