Probably is, but I would need a better picture to say for sure. There are at least 8 varieties of St John's Wort in the US, and some will grow in your state.
I don't have it here, so my knowledge if it is limited to what I read. I know the flowers are beneficial to insects, but not sure about the browsing aspects. This web site says that deer browse the foliage, but I doubt it would be preferred. St. Andrew’s Cross | Missouri Department of Conservation (mo.gov)