Sometimes when I first start driving, I get this awful noise from the back right. It’s almost like a “cans on a string” noise and it only does it in drive, not in reverse and it goes away after a couple minutes of driving.

 

is your exhaust rattling against something?

Or is there rocks trapped in your rim or behind the brake backing plate?

 

No I’ve checked that. It just happened in reverse this morning. Somebody told me it could very possibly be a wheel bearing.

 

i know you said you check the exhaust but my father in-law had a rattle sometimes from his truck. sometimes he would only hear it when he got on it but it wasnt always there. it got worse and come to find out part of his cat was broken up and rattling away.

that being said ive never hear a wheel bearing rattle only roar, thats not saying it cant happen but ive never came across it

 

you may have "Mud in the Tires"...like in My Cousin Vinny, but with rocks/pebbles.