Thank you both so much! Mystery Weed #1 is definitely Garlic Mustard. I pulled up about a half bushel of them today and also my husband drove over some with the truck and I kept thinking "Why do I smell onions? Are there chives hiding around here somewhere?". Also the photos I found online of Garlic Mustard look exactly like what I have. Cool! Now to find some tips on how to use/cook with them!
And Miles, you're right. They ARE serving a purpose already... I almost amended my original post to state as much but decided not to.
All the same, I'd like to figure out what they are for numerous reasons I won't go into for the sake of brevity. (They are growing under conifers - not sure what exact kind of pine tree - with limited shade and soil that hasn't been tested but is undoubtedly somewhat acidic.)
If anyone knows what the other "weeds" are I'd love the help!