I made a singleplayer world to test crossbreeding, and every time I crossbred wheat and sugarcane I got dandelions. Could be random but it happened three or four times in a row. I also got venomilia from dandelions and something, but accidentally trampled it before I could get more. Blackthorn was easy to get with 2 dandelions. Crop-Matrons are useful, but annoyingly require me to convert down to LV from my HV solar arrays.
Note: I found sugar cane to be the best starting crop, as it had highest base stats and grew fastest.
EDIT: The mechanic seems slightly different on Technic SSP and on Tekkit, but that might just be because Somnia makes it so much faster.