1/2 inch steel bolts... different sizes but w/e im not putting them all down
acorns
cucumbers
cans of cream corn
soda bottles
snow
airsoft bbs packed with wadding underneath.. cotton balls for a 1/2 inch barrel works great. good spread.
cap gun ammo.. shot it at rocks and watch them explode!!

\ steel bb's work good too especcially if they are really heavy.
d batterys work good on 1" 1/4" barrels. aa battery's for 1/2 inch.
cadbury eggs for 1" 1/4" as well
the famous watergun of course.
if you can think of anything else put it down