I thought it was golden Alexander from a distance, but as I got closer, I saw that the flower umbels were too large and too flat across the top. I do not know what it is. Those who grow dill will recognize it as a member of the carrot family, along with the white Queen Anne's lace that is a frequent non-native weed of prairie gardens and prairie restorations. On close inspection, you can see that each yellow dot of the flower cluster is actually a tiny flower all on its own, with tiny yellow petals around a greenish center. From my online searching, I suspect it is a parsnip, but I cannot tell if it is the yellow version of the native purple parsnip or a yellow non-native invasive species. So while it is lovely, I do not know yet if I am happy it is out there in that particular prairie!