Definitely get some white foam core, also if you dont have any modifiers bouncing off a low white ceiling works pretty well. Another thing you can try is using a tripod and taking a longer exposure then with the flash set to a lower power move it around to a few different areas and trigger it by hand, it'll take a few tries but you can get some good results.

Most of my more recent product shots were taken with only one speedlight and white foamcore to fill in shadows:





Of course the 57" brolly helps soften the light but you can achieve a very similar result by bouncing off a white wall or shooting through a white bed sheet.