I wasn't sure which ones were intentional or not, so I just tried everything I could think of that someone MIGHT want to put in a flowerpot.
I have seen this problem with two single chests next to each other (one trapped, one regular) with hoppers below each feeding into two furnaces. Filling one chest with iron ore, and the other with raw chickens, I've found chickens in both hoppers.
I wasn't sure which ones were intentional or not, so I just tried everything I could think of that someone MIGHT want to put in a flowerpot.