If those are plants you do not want growing where you do not want them growing they are "weeds". At this point in growth it is difficult to tell for sure which plant they may be since many have very similar cotlyedons as well as first true leaves

The largest seedling, nearest the Nasturtium leaf, is a Sonchus sp.

None of the seedlings is a grass.

Did you put seeds there, or expecting something 'good' from last year to have dropped seeds there? If not, anything unknown sprouting in such abundance would almost certainly be something you don't want.