Some invasive weeds have medicinal purposes, but the majority tend to be shunned and banished from fields and gardens.
I think I have happened upon a clever idea that won't make me rich at all, but instead make land recovery an organized process.
So what I would like to do is take on acres of canadian thistle for my example,
My approach to remove canadian thistle would be by applying quak grass and english ivy onto your canadian thistle patch, till it in, then watch them compete and pull the tops of thistle.
Now you have a quak grass issue where it's hot, and english ivy where moisturish. Throw in some Black berry roots to shade them out, till it up again!
eventually in 10 years it will become a blackberry thicket, where it otherwise would become a blackberry/thistle thicket. Blackberries are a big thorny bastard that is manageable by hand, but even quicker when you throw in the famished goats! watch them go..!
eventually you will have to walk around with a fork, and pull up those rhyzombials that linger behind, so maybe follow behind with pigs.
THat is my idea rant, accept it, or dont