What is this weed?
The first 2 pictures are of a grassy weed that has taken over our entire side yard. If uncut, it will grow over a foot tall. Loves sun or shade. Any idea what it is and how to control it safely? Some of it is growing near our 80 ft deep well so don't want to poison our drinking supply. What is picture #3? It seems to have flower buds near the bottom of the leaf stems. I believe it is an invasive weed? Any good weed identifier books so that I do not have to bother you in the future? Thank you so much!
Your first photos show a relatively new invasive weed for our area called Japanese Stiltgrass. It is covering large areas in both our yards, but also sadly in our natural areas, where it is outcompeting native plants.
Here is our page on it: https://extension.umd.edu/hgic/problems/japanese-stiltgrass
The good news is that it is easy to pull up, which is the preferred method near your well. If it has already started to 'flower' or set seed, bag it up and throw it out.
The link above gives more information.
The third photo shows another relative newcomer, Mulberry Weed. It is also easy to pull, and the easiest time to do it is in the spring when they are small. Get a grip low on the stem so you get the roots too or it will just regrow.
Definitely try to get it up before the 'flowers'- those puffballs, which will mature to purple, set seed, or you will have many more next year.
Here is an Extension page on it: https://www.uaex.edu/yard-garden/resource-library/plant-week/mulberryweed.aspx
As far as references, save our Weed Gallery page, which has photos and control help here, https://extension.umd.edu/hgic/weeds though we are happy to help you anytime!! That's what we do.
If you really prefer books, we often use "Weeds of the Northeast" by Uva, Neal and DiTomaso.