We think that your flower is a type of Daisy (Leucanthemum, not Rudbeckia).
There are multiple suspects for  chewed leaves and missing petals- beetles, earwigs, slugs, snails and beetles. We can see one small, shiny black beetle on top of a green flower, about a third of the way down towards the right in your first photo. They most often bite holes in the petals just as they are unfurling though.
Given the rainy/cloudy periods we had recently we are hearing about high populations of earwigs and damage from slugs.
Both eat at night so we suggest taking your flashlight and taking a look after dark.
Here is more about Slugs and Snails and how to manage them:
https://extension.umd.edu/resource/slugs-and-snails-flowers/

and Earwigs:
https://extension.umd.edu/resource/earwigs-flowers/

Christine