There may be other sources for hardwoods in the St Louis area, I have not really looked. St Charles Hardwoods has a good selection of native lumber, planed and ready to go in random widths and lengths. They have several common thicknesses. Quantities of a given stock item are not huge, but I am sure they can get you what you need. They also have some exotic species for special applications. I like that they will leave you alone to go into the warehouse and look for what you want. I have purchased poplar crown molding before and was very happy with it. They will make about any profile you need if you have a special application, such as matching something old. I’m sure that will cost, but some times there is no choice. I have found the people to always be helpful. I am not here a lot, but it is always where I go for anything other than framing lumber or sheeting. A minor gripe is that the warehouse is poorly lit.