a simple gist to create a grid of vertices

VerticesGrid.cs

// catlike coding

private Vector3[] Generate(int xSize, ySize)
{
    Vector3[] vertices = new Vector3[(xSize + 1) * (ySize + 1)];

    for (int i = 0, y = 0; y < ySize; y++)
    {
        for (int x = 0; x < xSize; x++, i++)
        {
            vertices[i] = new Vector3(x, y);
        }
    }
    
    return vertices;
}