i used flat head screwdriver to pop it off of the engine case.
never ever ever do this between two sealing surfaces that engineers demanded, at extra cost and time to the production of every engine, to be machined flat with a good surface finish. As an engine engineer myself, hearing this makes me cringe.
ok, lesson learned now you get to work triple. Lucky for you that edge there is where the timing chain runs from the crank to the cams so its a cavity that shoots straight to the oil pan.
1) So, i'd do something along the lines of draining your oil and see if it comes out first of all.
2) If not, i'd empty the oil catch pan and pour the same quart of oil repeatedly over that (and maybe every) cavity.
3) If that fails take the oil pan off and i'm 95% certain you'll find the piece there.
3b) You can take the risk of assuming that piece, or pieces, won't make it through your oil strainer, across the oil pump and end in your oil filter. It has nowhere else to go.
4) Refinish the sealing surface. Debur it of sharp edges, sand it flat and go as high as 400-600grit. If its not perfectly level, you will (and probably should) use a dab of RTV on that area too - as well that those specified in the manual. Don't just RTV the whole thing please... Think like the engineer that designed it, not like your buddies wrench and hammer things apart : p
Luckily doing the above isn't too bad. I would make sure every piece is accounted for.