i don't know what these flowers are. they're not daffodils nor tulips as their leaves are quite different. however, their centres look like that of tulips, with a stigma in the centre and surrounded by 5 stamens. their very soft yellow colour is rather attractive.
I do believe they are a small tulip. I had some in Michigan years ago, forgotten all about them till I saw you photo! Think I will order some for fall planting. Thank you!