This app was mentioned in 5 comments, with an average of 2.00 upvotes
https://play.google.com/store/apps/details?id=com.seeclickfix.memphis311.app&hl=en_US&gl=US
https://apps.apple.com/us/app/memphis-311/id993723645
Get the app and use it to report them. It's not perfect but it's better than you'd expect.
Related: Memphis does use SeeClickFix.com. They released an app for it, but it's really just a Memphis branded version of the main SCF app (I think).
Before you do anything such as file a complaint or report it to any government agency, you should always try to make contact with the citizen.
Try going over and knocking on the door, tell them about the rat problem you are having and that you see the rats go in and out of the trash heap.
I would go with the "bad for our health" talking points, ie: rats carry flees that are known to spread disease.
Bring it up nicely. Introduce yourself. If you're able, offer to lend a hand somehow.
If it doesn't go well, nicely end the conversation and file a complaint or report a ordinance violation;
You can download the official app for your phone, here;
or
Believe it or not, there is an app for that:
https://play.google.com/store/apps/details?id=com.seeclickfix.memphis311.app&hl=en_US