Does the sound move like something stuck in one of the plastic baffles inside the basket, or does it stay in one place? The baffles are not easily removable without damaging them, so if the object is in one of them, it might be a good idea to have a replacement handy.

So based on what you are telling me, it doesn't sound like it is in one of the baffles, but rather stuck along the outside. My suggestion would be to remove the lower access panel and in the middle you will be looking at the drain pump. Turn the clean out access on the pump (have towels handy) and let out any water and whatever else is in the sump. Then just behind and above the motor is the connection to the tub. Remove the clamp and take it free from the tub (more water here) then slowly turn the basket and see if you can find anything. This is the largest access to the basket without removing the front of the tub and the best chance for finding something as it is a low point in the basket.