How do I apply different textures onto a procedural mesh from a single image tilesheet?

I have the following code to produce a flat mesh based on the width and height specified in the Editor:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class FloorMesh : MonoBehaviour {
 
     public int width = 20;
     public int height = 20;
     public Texture2D texture;
 
     List<Vector3> meshVerts = new List<Vector3>();
     List<int> meshTris = new List<int>();
     List<Vector2> meshUVs = new List<Vector2>();
     Mesh mesh;
     int squareCount = 0;
 
     void Start() {
         mesh = GetComponent<MeshFilter>().mesh;
         Build();
     }
 
     void Build() {
         for(int x = 0; x < width; x++) {
             for(int y = 0; y < height; y++) {
                 GenSquare(x,y);
             }
         }
         mesh.Clear();
         mesh.vertices = meshVerts.ToArray();
         mesh.triangles = meshTris.ToArray();
         mesh.uv = meshUVs.ToArray();
         mesh.RecalculateNormals();
 
         meshVerts.Clear();
         meshTris.Clear();
         meshUVs.Clear();
         squareCount = 0;
     }
 
     void GenSquare(int x,int y) {
         meshVerts.Add(new Vector3(x,0,y));
         meshVerts.Add(new Vector3(x + 1.0f,0,y));
         meshVerts.Add(new Vector3(x + 1.0f,0,y - 1.0f));
         meshVerts.Add(new Vector3(x,0,y - 1.0f));
 
         meshTris.Add(squareCount * 4);
         meshTris.Add((squareCount * 4) + 1);
         meshTris.Add((squareCount * 4) + 3);
         meshTris.Add((squareCount * 4) + 1);
         meshTris.Add((squareCount * 4) + 2);
         meshTris.Add((squareCount * 4) + 3);
 
         /*
 
         meshUVs.Add();
         meshUVs.Add();
         meshUVs.Add();
         meshUVs.Add();
 
         */
 
         squareCount++;
     }
 }
 

I also have an image of different floor tiles. I want to be able to pass a tile texture in the GenSquare() function so I can specify what part of the tilesheet image to use for that specific tile. How would I go about implementing this? My limit of understanding seems to be that I know I have to put something in the meshUVs.add section commented out in the code, but I am unsure how to get the tilesheet to select a specific area of the image to use as a floor tile, and then how to correctly apply this to that specific square on the mesh. Any help is greatly appreciated.