I have no idea what to do for a cake that is for this boy who is turning 15. He lives on a farm and has a green motorbike he loves! Ideas?

why not do a cake that looks like a motorcross track, or maybe a tractor cake

Maybe have him jumping a tractor (or other farm related item...or animals...) with his motor bike.

what kind of farm? Pig? Cow? or do they even have animals?

If you use a tractor make sure you have the right color tractor. I know it might seem insignificant but most farmers have a preference to brand and are firm believers in it (kinda like the chevy vs ford in cars)

Since he is fifteen, I am sure he is thinking about driving....how about an old pickup truck with hay, animals and some other teen stuff.