is it possible to do this? I wanna change the key of some of these samples to match the key of the rest of my song. Logic 9 user here.

The only methods Logic offers for this are: 1) use the Pitch & Time Machine (performed in the sample editor, and it's a destructive operation so be sure to create backups first) 2) convert them to Apple Loops, at which point you can change their pitch by adjusting the key

Another option: 3) Slap a Pitch Shifter II Effect plugin on the track. Set to 100% wet and adjust pitch shift to taste. If you need the audio region permanently pitched bounce the region in place.