[Ag-eq] Jerusalem Artechokes

[Jewel]

    Does anyone know anything about these vegetables?  I exclude growing as, being a member of the 
thistle genus minus the thorns,  they do, very well, without any help from me.
I have 3 self-sown bushes and I would like to get some useful return from them.
They have some huge flowers on them, some are about 8 inches in diameter.
Two of the bushes have fallen over and the third is heading that way, but the roots of all 3 are 
still in the soil.
Is this what is supposed to happen?  From the little information I have been able to gather, the 
seeds from the flowers will burrow into the soil and will become sort of potatolike things which I 
can treat as such:  that is:  boiling/baking/roasting.  Is this correct?  If so, Jerusalem 
artechokes will be the only * thistle that I do not declare open warfare upon!
When digging out my eternal crop of weeds, should I avoid disturbing the soil in close vicinity to 
these flowers?
I suppose that a little gentle investigation wouldn't do any harm because I have been told that once 
you have one successful J A, you will have them forever!

           Jewel