Parts of my lawn are full of these. I thought they were weeds when they were smaller and now they are looking like tree saplings. Is that what they are? Maple saplings? How do I get rid of them from the lawn?
Just mowing will take care of this problem. What I am more concerned about is the health of your lawn. No seed, weed or otherwise will be able to germinate if you are keeping your lawn mowed 3 to 3 1/2 inches, no lower. There is an awful lot of dead stuff in your grass crop and I think I can see a fungal disease called Red Thread.
When your lawn is maintained correctly you will not have weeds, you will not have baby maples either. Do you bag your clippings and then compost? Don't allow clippings to lie on your lawn. I've never found a REAL mulching mower and don't expect that to happen. Bagging is a very good thing and those clippings are incredibly useful elsewhere.
Here is a check list...
Aeration: Pulling plugs of soil and grass out of your lawn and let them disintegrate right where they lie. Once per year. Rent and share with neighbors.
Water: Only water when you are able to see your footprints, blades of grass staying down after you step on your lawn. And then water very deeply. 4-6" deep. You should be using 1" of water per week when you get your grass roots trained. You'll never have to allow your grass to go dormant. Or do you water everyday for a few minutes?
Mow your grass HIGH. How short are you mowing your lawn? I am guessing cool season grass mix lawn...where do you live? Mowing your lawn any shorter than 3" will make your grass crop WIMPY. Your grasses won't be able to out compete weeds, diseases.
What is your fertilizer schedule? What are you using?
What are you doing for the edging?
Have you used lime, moss control or any fungicides or pesticides?
Sharp blades, always.
This baby maple is not a problem. You should be mowing once per week no matter what. Twice a week is fine as long as that grass never gets below 3"...(there are major reasons for this length) I wouldn't even bother bending over to pull it out of the lawn but pulling out the baby weed or maple is a done deal for the weed. Throw in compost. If you raise your mower to the correct height of 3" 3 1/2 is far better, you won't be able to cut this little maple. Once the top of that maple gets over 3" high you will be able to chop it/kill it. Or pull it, easy peasy. Will not grow from roots or a beheaded stem.
I would grab a metal leaf rake and rake your lawn to remove the debris somewhat. Do this before mowing because the mower acts like a vacuum cleaner as well sucking up the debris off the lawn and putting it into the bagger. I also pluck weeds out of beds and throw onto the lawn before mowing. The mower sucks up the weeds, leaves, debris for you. Then dump in compost pile or on stubborn weedy areas.
Fertilize with (hate to do this but you have to try Dr. Earth's Lawn Fertilizer, truly amazing fertilizer that comes with thatch-eating bacteria). More expensive but lasts longer. Slower to show green but that is a good thing for your grasses.
If you are interested in improving your grass crop called a lawn, we got lots of other questions and answers you might find interesting and will eventually save you lots of money on water and products you do not need.
Do you know the pH of your soil bed? Describe in detail what you have been doing for maintenance of your lawn if you are interested. I really know this beast...cool season grass crop. d I was turning away potential clients. In Seattle.
Check out the other answered questions about cool season lawns on our site. You'll have questions so send them to us?