First two are St Augustine. Centipede has pointed blades. St Aug has rounded blades at the tip. Third is bermuda. Fourth looks like either fescue or Kentucky bluegrass. First weed could be crabgrass. I am unfamiliar with the rest of the weeds. Crabgrass is fairly easy to get rid of in St Augustine. Go to YouTube and search for St Augustine, crabgrass, and baking soda. There is a slide show posted by a member of another lawn forum.

GreenBlood10, run your finger and thumb up and down some of the blades a few times. If the upper surfaces of the blades feel rough, you could be looking at quackgrass. Orchardgrass, on the other hand, has smooth-feeling leaves (aka "blades"). Also, quackgrass has narrower leaves than orchardgrass whose leaves are wider. Orchardgrass is a coarse-textured bunchgrass. When it comes to grasses, coarse and fine texture refer to the width of the leaves/blades, not to their feel. It's a bit confusing because in most areas, "texture" refers to how something feels--the tactile sense. But for grasses, texture refers to the width of the blade: narrow or wide. For most grasses, narrower leaves/blades are usually spaced closer together, meaning the grass has a higher shoot density (more shoots per area). These grasses are said to have a "finer texture" than grasses with wider blades which have fewer shoots per area. Kentucky 31 tall fescue is a coarse-textured grass whereas creeeping red fescue is a fine fescue. Cultivars of K 31 have been bred to become less coarse, and so look more like Kentucky bluegrass than Kentucky 31 tall fescue. Gets confusing right? Both grasses have the word "Kentucky" in them. Lots of grass history has happened in Kentucky. Zoysia is somewhat of a beautiful oddity because its blades are moderately coarse yet the grass looks so good because zoysia blades are spaced so close together, considering zoysia's medium coarseness (or moderate sized blade width).

Could be, or somebody brought the seed in on their shoe or attached to their pants. Or in a rabbit's fur, and so on. Seeds have tons of ways to get around, all of them pretty effective. It does look like K-31 or one of the even less well-bred fescues. A shot of Round Up will take it out, as Tom noted. Or dig out. Common lawn herbicides simply have no effect on that. If you have appreciable Kentucky bluegrass, the spot will fill in. If not, you'll have to reseed.

The first thing you need to know is that it is not a grass but a broadleaf plant. There are selective herbicides which work on most broadleaves and leave the grass unharmed. Weed-b-Gon would be the first thing to try. Weed-b-Gon Chickweed, Clover, and Oxalis Killer would be the thing to try if the first WBG did not work after 3 weeks. If neither one of those works, then RoundUp painted onto individual leaves would work. There is another method to try, but try the WBG first.