What do the leaves smell like ?

Also, could you post a picture of an un-dug up plant?

I am not sure what they smell like. If I get another one that comes up I will take a whiff and post another picture. To add to the description...I have several of these that are popping up in my lawn and around the edge of the lawn(in the rocks). They have a crazy root system and they all seem to be connected with long thick roots. My neighbor just cleared out a bunch of plants and trees in their backyard. And I think one of their plants/trees is trying to survive in my yard. I have been digging up the plants and pulling up the roots(up to 5 feet long) before they break off.

My "GUESS" , and I mean guess, is that it is Oleander growing from spreading roots.

Reminds me of oleander as well. Do they grow in AZ? Do they sucker like that?

Oleanders do grow in AZ. Just looked this up. Oleander roots that remain in the ground may still produce suckers that appear above the soil line. ... If they grow larger, they may form a dense root system that is difficult to remove. These sprouts, along with the rest of the oleander plant, are poisonous.

Oleander leaves have fairly distinctive veining. I cannot see them clearly enough from the photo, but they can be seen at this link for comparison, the right photo at the bottom of the page. https://rangeplants.tamu.edu/plant/common-oleander/  The leaf arrangement is opposite or whorled on mature plants, but I don't recall if they are arranged differently when young.

When they are young they are different. Not as distinctive. These look like the oleanders that I see on the way to a meeting house I go to.