I never did that, but just because it's about losing things, last year, some girl's purse got in my bookbag somehow (I guess some idiot put in there for a prank...). I never got the chance to turn it in, but later, the office announced on the "unicorn" (I think it's unicom or something, but I can't spell it and saying speaker is boring) a red purse was lost, so I finally turned it in. :P Not a cellphone, but too bad. And yes, it turned out I DID have the purse, thank you for (not) asking. :3
The toilet. Oh wait...I dropped it in there. Whoops. But I've also found it underneath the couch somehow...?
I found it in a tissue box once. D: I didn't ask how or why xD
lol.nice xD
In the crack between my bed and the wall. But that's not unusual, because it's always next to my head because it's my only source of an alarm in the morning. MLIA. :c

I lost mine in a buss once... the driver was nice enough to call my mother when he found it xD as in.. he pushed down my number-list til he found "mom" and called xD
i also found my cellphone in the house of my friends mother... i mean WTF? if it was the friend it's understandable but her MOM xD well apparently i lost it when i was with her eating pizza there.. I've also found it under the bed, within my brothers room, behind my cacti and inside my rat's cage..