I'm not sure what you mean by a gardening system.
There is an inventory in SO, yes, but I don't know if the tokens inventory system exists. The The Sims the inventory system did not hold or keep track of objects. It kept track of little controller files called tokens. Those would hold a few tidbits of information about the item they are representing. Like how many of them a particular Sim "has" in his inventory or how much the item should cost when purchased.
HArvesting crops is noting more than the plant reaching a certain stage and making th harvest interaction available. When you take that action it resets the plant object to a starting point (or to a "pre-fruited" stage) and pops the appropriate inventory tokens into your Sim's inventory. Putting your harvested crops into a pantry is done by the Pantry checking the Sim's inventory for the correct token, testing that the Sim has a high enough quantity and, if so, then reducing the quantity by X amount and adding X amount to it's own "quantity"/food level attribute. There's no actual "carrot" object anywhere in the game.
While in the case of carrots there isn't an object there COULD been one. The Magazines bought downtown are actually two separate iffs: a purchase token and an actual object. When a Sim is delivered home in the Downtown cab it root around in their inventory looking to see if they purchased magazines and, if so, pushes an action on them to make them carry the item into the house (i forget if they hold the object or if they just have a prop in their hand to start with) and place it (the object) onto a surface (the vacation island shuttle does the same for souvenirs). The magazine purchase token then deletes itself from the Sim's inventory and the whole thing looks like the Sims took something from his "pocket" and put it on the coffee table. The one on the coffee table is actually the second/separate iff, however, with it's own coding (for reading and changing personality points.)
It is possible that TSO's inventory system is the same thing with more elaborate tokens (that keeps track of a LOT more details than TS1 tokens do), but the fact that Rhys got signs to keep their text even after they are put into inventory suggested to me that the inventory system was probably a different one. (Then again being able to write text to an object like that is sufficiently different from anything I have been able to do in TS1 that I am on very shaky ground on this subject) If it is I wonder if it have replaced the simple token version or if it might mean we have both available to us which would be fantastic.
