Just one household (I think that's all you can have in the console version), 2 sims. Nothing really changed, I haven't used any cheats or the console "karma" powers. Between the time a planted the first little garden (I think three tomato plants, a couple lettuce and an apple tree) and when my inventory (the personal sim inventory and/or household) went blank nothing had really happened except going to work. I noticed the first time I went to harvest (a couple days later for those plants) that nothing showed up in the inventory and that I had lost some stuff, however the inventory bar shows the inventory is still about a third full and everything shows up if I try to fertilize the plants (not sure what good fertilizing an apple tree with a grape seed would do though). I tried picking up new seeds from around the neighborhood and for some reason the only ones that would show up in my inventory were the "unknown" ones, all others didn't show up (but uncut jewels and space rocks did).
Also to make it stranger, the sim was working in the garden after the inventory went blank, she got hungry and pulled an aplle out to eat. Also if I go to the market an option still opens up to sell the produce that I harvest (but doesn't show up) and it works fine. I just can't plant anything new or carry on the good plant lines.