Leaf spring question?

So ive got 4.5" leafs and inbetween each leaf theres like this round dish that hard, i dont know or even have a clue what they are, what are they and what do they do? b/c on my driver side, one of them is starting to fall out and isent going to stay there for much longer.

they are little pads that help to prevent squeaking. You could try to push it back in, but it will evetually get spit out. With I knew where to get soom, mine fell out long ago.

o ok well that would explain my im getting alot of squeaking in the back now lol