When throwing items onto a light weighted pressure plate placed directly on top of a hopper, the items go through the pressure plate into the hopper. However, if the hopper is delayed using the following method, it will stay powered and not suck up the items:
1. Place these blocks in the order as follows: hopper, redstone block, extended sticky piston facing the redstone block
2. On a different side of the weighted pressure plate, place two redstone dust, then a redstone repeater, followed by a path with a NOT gate to the sticky piston (the piston should be extended so the redstone block touches, and thus powers, the hopper)
3. Throw 5 items onto the pressure plate to activate the redstone path, retracting the piston and pulling away the redstone block
The items will remain on the pressure plate, powering the path perpetually and keeping the hopper powered.
NOTE: This may or may not be due to the redstone dust one level higher than the hopper. The pressure plate by itself does NOT power the hopper and the hopper sucks the items as usual.