 laddonia is a city in audrain county, missouri, united states. the population was 513 at the 2010 census. ==history== laddonia was laid out in 1871. it was named for amos ladd, an early settler, and his wife onia.{{cite book | url=http://books.google.com/books?id=rfauaaaay
Cities_in_Audrain_County,_Missouri Cities_in_Missouri