Owyn's suggestion of altering the map with CentreED or CentreED+ is really the preferrable method...especially since we are approaching 2020 and internet speeds just get better so distributing files to players should be a moot point.
I strongly encourage this route as well, because if you do what Owyn added as another suggestion (with Pandora's Box and such) you are just adding a ton of items to your server and thus increasing your item count for nothing more than decoration. So I feel the rule of thumb is that if players are not going to interact with the items...then put them right into the map files. If...for example...you could use Pandora's Box to put spoons and cups on a table to decoration it, you might as well just add them to the map file unless you are going to let the players drink from them or steal them.
Before map editing was a popular thing to do, people would decorate their worlds in-game which just made for a clumsy user experience. Items would appear on screen very oddly and when you would do a CONTROL-SHIFT to bring up names, you screen would get spammed with a ton of decoration names.
The maps I make have 100% of the decorations built right into the map. I couldn't imaging my item count if I didn't do that. Things like doors, switches, or other interractive items (items players can double click for an effect...or items that have scripts that interract with the environment) are the only items in my world decoration files.