Hard to tell, it's still so small.

Looks kind of like a begonia but they are seldom done from seeds.

Otherwise there is no way to know - maybe not even when it gets bigger - unless you can narrow down the options you planted there.

Dave

I agree it looks like a fibrous rooted begonia, sometimes called a "wax begonia". I do grow them from seed but not in the open ground. They survive the winter here, but not sure about your location. Al

You need to post a list of the seeds you had on hand so people have an easier time figuring out what it is.

Could it be nasturiums?

It's definitely not Nasturtium - they self seed all over my allotment and don't look like this