It's a frilly poppy. If you like it and want some more, leave it to make a seed head. Leave that on until it looks dry and brown and the little holes open round the top. If you shake it you will be able to hear the ripe seeds rattling inside. Collect them in an envelope or paper bag by cutting the head off and shaking it upside down into the bag. Then you can sprinkle them wherever you like and you will get lots more poppies next year.
One of the many varieties of Papaver somniferum aka Opium poppy https://www.sarahraven.com/flowers/seeds/poppies/poppy_somniferum_mix.htm
Thank you very much indeed