Growing mustard

Specifically for the seeds rather than the greens.  Anyone in the northern part of the country tried it?  It looks like its a late summer crop, cause the plants actually need the cold to produce large quantities of seeds…..anyone have any ideas, tips, variety suggestions?  I don’t know that I’m going to try it this year, but its come up in discussion between hubby and I several times now so I decided its time to start researching….