Successful objects include a Leinie's bottle:

There's usually one of these around somewhere. Very subtle markings, once I figured out how not to glob the paint onto the glass.
And a rotting onion half I found in the bottom of the fridge:

Very cool, although future onions will produce (hee!) slightly different patterns. The fabric smells slightly of onion; I will have to rinse it after I heat-set the paint (does that take a hyphen? "heat" modifies "set"....).
And now, if you are my mother, you want to know what I will do with these. As always, the answer is "store them somewhere until I think of something." Except the styrofoam packing peanut piece--that'll be a back or base of something, where it can never be seen by human eyes.