. Best bet is to buy ergot or grow an ergot culture or even extracting it from seeds would be a better option than trying to get it from cafergot
Some people are not as lucky as you are to have a source. I doubt anyone would actually be enthusiastic about growing a culture. That really leaves seeds as you mentioned, which can be a pain in the ass too.
Besides, if you just happen to suffer from migraines, its not bad to have the pills (Ergomar, no caffiene) around. ;)
Cheers...