This thread is for all those unplanned weedlings that may be invasive, edible, or not a weed at all!
Near my garden and my herb bed, in the pathway, is this tiny yellow flowering weed.
This is US, WA state.
Name That Weed!
(Prize for good answer is a heart!)
Looks like alfalfa to me.
Trifolium dubium?
Looks kinda like a small clover that grows here…only it’s bloom is kinda pinkish purple
Hop clover
Wild spurge
Black medic? Medicago lupulina
I’ll say either hop trefoil ( Trifolium campestre ) or lesser trefoil ( Trifolium dubium)bb.
Going with @Bradybb on hop trefoil (Trifolium campestre). Look at that last picture, the bottom trifoliate leaves. The petiole of the middle leaflet. It looks longer than the lateral ones.
The other Hop Clovers that occur in Illinois, Trifolium aureum (Yellow Hop Clover) and Trifolium dubium (Small Hop Clover), are similar in appearance, except that the middle leaflets of their trifoliate leaves have petioles that are no longer than the lateral leaflets (they’re often sessile, or nearly so). In Low Hop Clover, the petioles of the middle leaflets are conspicuously longer than the others.
Hey a lot of you have good guesses. It is not an easy match. I will have to carefully examine the leaves and flowers to figure out best match. This is not a weed I have noticed before here. It is not growing in other areas of the apartments.
In my opinion, all self propagated unwanted vegetation is weed. They could be invasive or easy to deal with, but they are all weeds. In my garden, dill is the weed. I planted it once and let it grow to seeds to collect them for food and here you go - it is everywhere now. This year weed is garlic! I dropped some leftovers in the crack of the steps few years ago and got a cluster of garlic well contained withing the crack. Last year I missed to remove scapes from it. And here you go - whole garden bed below it now is covered with tiny garlic starts… 
Hhahahaha! I am imagining garlic in sidewalk cracks! Dill replacing grass! Well at least edible weeds!
Another “weed” was planted in my yard and neighbor’s by birds. It began to look like a vine, but clearly it is now a tree. What tree is this weed?
Looks like Birch tree
I think you are the winner.
I will share with neighbors it is likely a birch of some type.
The picture made me pause for a minute, because the bark looks like a water birch, which I thought were only native farther north of you. Paper birch should have a lattice on immature bark from what I understand. Oregon State says water birch aka red birch “native” though.
Bingo!!
Winner!
We had some of those drooplets in the yard from wind. It must have seeded well!
Can anyone identify this weed plant …grows upright///few feet tall…that blooms with purple flowers (sort of like liatris) and the bees love them …it comes back every year and it has a massive rootsystem (pulling up the plant results in a considerable amount of soil.) I leave some of it because the bees go crazy for it.
