Weeds or not?
Are these weeds? Or some happy accidents? Or regrowth from last summer‘s garden? If the one with the tiny white flowers is a weed, could I re-plant those weeds all together and make a pretty little ground cover? Or is this plant invasive and should I aggressively pull it all up?
The plant in the first photo is called hairy bittercress. Typically it is considered a weed. It is a prolific re-seeder! https://extension.umd.edu/hgic/topics/hairy-bittercress
We are not quite sure about the second one. Do the leaves have hairs? Prickles? Is there a milky white sap when you tear a leaf? It does not look like an ornamental plant we recognize. We may need to see it in flower for an accurate ID.
The third one looks like a young mugwort seedling but there are some ornamental plants that have this leaf shape too. Did you have ornamental plants with this leaf shape in the garden last year? (Chrysanthemums?) If not, it's probably best to pull it out. Mugwort is a tough one to get rid of if it's that. https://extension.umd.edu/hgic/topics/mugwort