1- Harvested weeds often go into my pallet grow boxes. When I have time, I'll chop them up first with a lawnmower before dumping them into a box. But when I'm short on time, they will get chucked in whole. Yes....seeds and all. I don't bother taking the time to handpick out the seeds. Most seeds will die when the pile heats up, so it's not a problem.
2- Another good use is to use them as fill for one of the hugelpits. Again, I'll chop them up before adding if I have the time. Otherwise they go in whole.
3- Today I had a good pile of weeds, mostly Bermuda grass that the community gardeners removed from an unused garden bed that's being put back into use.
And also a pile of assorted weeds that have been drying out for a week. Time to grind them up, lawnmower style.
I used the ground up weeds to apply extra mulch to some young potato plants. These chopped weeds will dry out over the next couple days and thus won't root and be a problem. Occasionally a few of the Bermuda grass stolens survive in the loose mulch, but they are easy to pull out if they start showing any signs of regrowth.
Most of my gardens are mulched regularly, so weeds are not a serious problem anymore. They only get out of hand in beds that don't get mulched in a timely fashion. Yes, if I don't pay attention to a particular garden bed, the weeds & grass take over, though I'm getting better at keeping ahead of things.
My main "weed" source now is my pasture areas that I'm upgrading. Plenty of ferns and rough brushy stuff to harvest. But the gardening areas have gradually become less and less weedy.
The one thing that I no longer use weeds for is making my compost. It's just easier and quicker to use grass clippings.