Creeping buttercup, ranunculus repens - nothing desirable about it :) You're going to have to stay diligent to get rid of it, stay rid of it. Common in W Washington and W Oregon, if you find it returning after you've dug it out, you may have missed some roots - and the seeds are viable for many years. Possibly try spot treating the 'resprouts' with some like Scotts Ecosense Weed Be Gone for lawn weeds, it may help you gain control. Here is a link that might be useful: Creeping Buttercup

If it is nut sedge and it looks like it except for the little bloom, maybe I kill mine before that comes on. You can not get rid of it by pulling it out. There is a special spray that will kill it by Ortho if I remember right, $8. It may take 2 or 3 applications. The reason you can't pull it like most weeds is there is a little nut on the end of the roots that will not come out when you pull it. It breaks off and grows into another plant. It likes wet places to grow.

The top half of photo 5 also might be creeping charlie (which my niece discribes as smelling like herbal shampoo) AKA Glechoma - photo 2 might be also. I agree with Nepeta (cat mint, not catnip) on 1, thyme on photo 3 Not sure about the bottom half of 5. 4 might be Rudbeckia with perhaps wild carrots (feathery foliage which would smell like carrots if it is) AKA Queen Anne's lace.

Yes, I think that one has been on the list for a while now. I got a firsthand look at how invasive it can be at my house. I lost an entire bed of rudbeckia and echinacea because of it. The only good thing about it, is that it pulls up very easily. I read up a bit on it last year. Apparently it is best removed later in the summer. That way when new WEEDlings come up from the seed bank, they don't have time to produce seed and are winter killed. Another method is to continuously mow it down.