They're much better greens, both nutrition wise and (in my opinion) taste wise, than any commercially produced greens and they're free.
A few jars of wild greens in the pantry to go with pinto beans and corn bread in the dead of winter is heavenly comfort food.
Last year I thought I was doing pretty good in putting up enough, but the last jar was eaten long before there were enough wild greens out there for a meal so this year... I'd better get busy!
I've also been picking purslane when I have time. I pickled a few jars last year and they were really good. I've dehydrated purslane, frozen it and canned it plain but wasn't happy with it, so it's pickled or nothing. Since it's so healthy, I'll just get used to eating it with everything.
Besides the cost saving of putting up free food, it's more than worth the trouble in another way. Wild foods are generally healthier than domesticated home grown food and quite a bit healthier than most commercially grown food.
For instance, purslane is one of the very few excellent vegetable sources of Omega 3 fatty acids.