:D of course!! I am using 3 fake plants out of the 5 in my tank that came from a dinosar b-day cake. I also have a gorgeous blue glass whale sculpture in there, and some pretty glass stones. IDK if that qualifies as 'household' items, but it's cretainley not from a store so! Also a tip on gravel.... you don't have to spend money on special aquarium gravel. I mean, you can, and their cute and colorful, but in the sorta natural look of my tank i prefer nice 1-2 cm pebbles as gravel :D
P.S) ALWAYYYS make SURE that objects are O.K to put in ur tank or bowl or w.e before you plop them in there!!