Looks like you have a Post Mint Damage Dime. It's called a Spooned coin. Someone took a spoon or hammer and hit the edge a few times to flatten the edge. Worth - 10C
Yep, dryer coin is my guess as well. Think about it. You leave a dime in your pocket, it pops out in the dryer, around and around she goes, rounding off the edge. Dimes and cents most likely to be overlooked in your pocket. Might be tougher to find a half like that, I would imagine it would make a lot of noise in the dryer.