For me, it is most harvestables. It doesn't matter if I found them in the dumpster, harvested them from the neighborhood plants, or grew them myself. I will sometimes find them again in the household inventory but then I cannot do anything with them. I cannot even drop them on the ground to retrieve them. At that point, I can only sell them from the household inventory and give up.
Just to add to this, my sim found a morel mushroom (comes with Outdoor Retreat) while diving for deals. I dragged it out of his personal inventory immediately and placed it on the ground for him to plant and by the time he got back the mushroom had disappeared from the ground, so even if you take it out of the inventory immediately it can still disappear afterwards.
Best regards,
Jennifer
No mods/cc, game version PC: 1.63.136.1010, and all the packs up to an including Eco Lifestyle
