Here are a couple of images from my vintage post card collection in honor of this beloved flower:
They are both pre-1923 and, therefore, in public domain. Please have fun using them for your personal projects!
In case you don't know how to get these images onto your computer:
Windows OS users: left click on the image and choose "Save image as ...", change the file name to something that makes sense to you and then save it your chosen file saving place.
Apple OS users: hold the Control key while clicking on the image and choose "Save image as ...", change file name and save to chosen file. (I believe you can also just drag the image to where you want it to go but my Mac died a couple years ago and I can't be sure.)