Annual Poison Oak Show at the St. Charles Saloon in Columbia State Historic Park. Aren’t you just itchin’ to participate? This event is like a traditional flower show, except all entries must include poison oak! Some of the categories are: best arrangement of poison oak, most original poison oak dish (with recipe), best photograph of poison oak, best photograph of poison oak rash (or in person). 10 am for entries, judging at 1 pm.