The pyramid with the life fruit is the only place I know of in game that it grows. Otherwise you have to go to buydebug to place life plants in town.
However, if you go to that pyramid with it in the room, and harvest it, and then come back a couple of days later, you might have enough. Make sure your sim has the prepared traveler reward to help with this. That particular pyramid is in an opportunity chain, but it's the one that starts with the newbie quest. Without a moodlet manager and/or level 1 visa to start, one trip may not be enough. You have to do a couple of tombs before that, but with a moodlet manager and knowing where to go, it goes quick, especially if your charisma is high for the parts of the opportunity chain that require you to talk to locals.