In Riverview, there are three spots where special seeds spawn, when my sim picks them up, usually there around 5, three are usually money tree seeds, one is deathflower and the one is a life fruit seed. Sometimes it is the other way around, so I accumulated quite a few money trees and life fruit plants. I have talked to the plants and really not noticed any difference, but I probably wasn't paying attention on the upgrade, will have to do that. Not sure if the location of the seeds is different for every bodies game, but I can write where they are and I guess we can find out.