It all depends what your goals are. Where do you want to be in one season versus 2-3 seasons versus long term?
Weeds are nature's emergency ground cover. They do a great job. They're slow to build soil, though. If you want something faster you need to take action. But the weeds that are growing there are there because they are well adapted to the site, so you might consider how to incorporate them to one degree or another in your near and possibly long term
plans.
Buckwheat is a great nutrient scavenger, is super competitive, and its succulent nature means it will readily breakdown and
feed the crop that follows it. It does not play well with others, though. It's easily killed by frost but can readily self-seed. Oh and
bees LOVE it. So do
chickens.
Will clover grow for you there? A shade tolerant variety can fix nitrogen below other crops and most are perennial, so great for a no-till or food forest application.
The sky's the limit! Your
land looks very pretty. Have fun with it and good luck!