good or bad "weeds"?
My neighbor has let the hill behind his house go natural/wild. The picture shows some of the plants I've seen there: ajuga, virginia creeper, creeping charlie, english ivy (which has already invaded and taken root), even some poison ivy, and a shallow-rooted plant that might be a kind of basket grass (does not seem to have wavy leaves, but spreads quickly). This is the first year I have noticed this plant. Which plants should I try to keep out of my yard? And what is the best way to get rid of them? Thank you for your help.
With the exception of Virginia creeper, these are all non-native invasive plants. You do not want any of them in your landscape. Unfortunately, because of the abundance of aggressive alien plants, it is impossible to let an area "go wild" (hands off) and have a natural native habitat arise, as your neighbor is trying to do. People need to help "nature" along by removing the non-native plants so they don't smother the good plants. Here is more info about this problem: http://extension.umd.edu/hgic/earth-friendly-landscaping
Please click on Weeds on our homepage. The invasive ones have an asterisk. You will find info and help with stiltgrass and creeping Charlie there.
For help with English ivy, here is the weed profile page of "Weeds Gone Wild" which is all about Invasive plants: https://www.nps.gov/plants/alien/factmain.htm