Looks like a mimosa to me, though some weeds look similar until the tree gets a little larger and shows a woody stem. Be careful where you let mimosa's grow as they can be about as bad as a weed. My daughter has them sprouting up everywhere in the yard where the grass is not cut, and keeping them pulled is a constant battle. I love mimosas and seem to be able to grow them on my dry sandy hill without the seeds germinating so much, causing that profusion of unwanted trees.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.