Advice On Correct Wax Ring ?

This is a follow-up post to my previous post entitled " Unusual Alternating Toilet Flushing Pattern ".
I pulled the toilet. HJ was correct. The wax ring ( with no boot ) was matted with Palm tree roots. A big root surfaced on each side of the flange where the floor bolts are mounted. One of these roots entered the sewer pipe. I pulled a 3 foot long bundle of Palm tree roots out of the sewer pipe. The flange is in good shape and sits flat on the cement slab. The opening is 3 1/2 inch diameter. I don't see any bolts attaching the flange to the cement. Does this indicate that the plumber probably just glued the flange to the sewer pipe ? The linoleum sits slightly above the level of the cement. It's also aged and curled on the edges and the plumber packed the area with alot of caulk. There are 3 washers stuck to the cement where the front of the toilet sits on the cement. I assume that these are shimms ? Please help me select the correct replacement wax ring. In my area I am pretty much limited to buying it at ACE or Home Depot. Thanks much for any help on the wax ring or any other reinstall advise that you have.

You will find 4 or 5 slightly different wax rings in the store. Ask 20 plumbers and you will get 25 recommendations about which is "the only one to use".

Don't lose sleep over it.

I mentioned that the diameter of the flange opening is 3 1/2 inches. I noticed that the metal flange has a plastic or rubber insert in it. Without that insert the opening looks like 4 inches. It looks like that insert can be pulled out. What is this insert for ? Was it part of the wax ring ? It didn't appear to be attached to the wax ring. Can someone please explain what this insert is ?

That was part of the old wax ring. They come with and with out the insert. Stay away from the one with the insert. It can cause a obstruction that can result in a stoppage.

John