Hi, Those look a lot like sunflower seedlings. Is your pot located near a birdfeeder? Sometimes birds or squirrels will drop or hide seeds in planters for later. 

They could be something else, but it will be easier to identify once the plant has it's first set of true leaves. The leaves shown here are the cotyledons, or seed leaves, which are not as helpful for identification as the true leaves for many plants. 

The scale is a little hard to tell in your photo too. I don't know if the plants are larger or very tiny. If you send me a follow-up photo, put a quarter or pencil or something next to the plant to show scale a little better.