Another great photo!
Is it a Coreopsis Marge? Foliage looks about right. Ive tried to grow C. rosea 'Amerian Dream' a few times. It was easy from seed, but I couldnt get it to do well for me. At the same time I grew C. verticillata from seed. It survived in two locations for a few years now, but it isnt spreading the way I'd like it to. Ive heard reports that its invasive! Certainly not in my garden.
This season? it has only started to flower a few weeks ago, in September. Nice little plant but I have to mark the spot. Its a brown patch all summer. Patience required!