Dear Julia,

Thank you for contacting us about the weeds in your lawn. It is rather difficult to positively identify small plants from photos. However, the weed in the first two photos may be Corn spurry or stickwort, a common and widespread weed (note this fact sheet is from Canada): 
https://www.ontario.ca/document/weed-identification-guide-ontario-crops/corn-spurry

The second weed looks similar to several plants. It may be chamomile or cilantro which have become naturalized across much of the US. Does it have a smell? Are the leaves sticky or smooth?

It would help to know what type of soil you have (sandy, clay...). What type of lawn seed did you use and where did you purchase it? Was it prebagged or in bulk? With some additional information, I may be able to help you identify this plant.