squeeks like a hay trailer

2015 TRD OR - 45K miles. 2nd owner. 100 deg heat 1 month ago resulted in a squeek which makes the truck sound like a old farm hay trailer. I hopped on the back bumper and jumped a bit; the noise was there but not as pronounced as I would have thought. Any thoughts or warnings before I take it to a shop? I live in the Des Moines, Iowa area but cannot find a truck/4x4 focused shop. Thanks. (and no - I am not a farmer - the hay trailer comparison actually came from my teenage daughter).

 

It’s probably dirt in the rear leaf springs. Happens on my truck too. Usually after a good washing they quiet down. Or Sometimes one or two will slightly turn and rub against the retainer thing

not really any good shops around unless you want to road trip to chicago, KC or Denver.

 

As stated above. Also worth inspecting the leafs in the spring pack to make sure one has not broken. Has been known to happen on Tacomas.