collidepoint wont detect box being clicked on

I am making a game in pygame, and so far, I am just on the screen where you pick your characters.

My problem is that I have a list of pygame.Rects, (Technically, it is my own class derived from pygame.Rect, but the only changes I have are methods to have it be shaded or underlined.) and when the mouse is clicked on the box, I want it to be underlined, but my main point right now is getting it so that it can actually respond when it has been clicked on.

A runnable example:

import sys
from pygame.locals import *
import pygame as pg

WIN_X, WIN_Y = 800, 600

def Box(size, colour, pos, alpha=None, image=None):
    '''
    return a square rectangle, surface pair
    uses MyRect
    '''
    print(pos)
    new_surf = pg.surface.Surface(size)
    new_surf.fill(colour)
    new_surf.set_alpha(int(alpha))
    SURFACE.blit(new_surf, pos)
    if image is not None:
        SURFACE.blit(image, pos)
    return new_surf.get_rect(), new_surf


def main():
    global SURFACE

    pg.init()

    SURFACE = pg.display.set_mode((WIN_X, WIN_Y))
    test()


def test():
    surf=pg.display.set_mode((1000,1000))
    box_list = []
    for i in range(WIN_X // 4, WIN_X // 4 * 3, 100):
        box_list.append(
            Box((25, 25), (211,211,211), (i, WIN_Y // 2), 150)[0])
    while True:
        for event in pg.event.get():
            if event.type == MOUSEBUTTONDOWN:
                x,y = event.pos
                for rect in box_list:
                    if rect.collidepoint(x, y):
                        print('box clicked!')
            elif event.type==QUIT:
                pg.quit()
                sys.exit()
        pg.display.update()

if __name__ == '__main__':
    main()

I have been trying to get around this for HOURS and nothing has worked. (By the way, I am relatively new to pygame, so if you see any possible other problems, please point them out).