From the Lawrence Daily Journal-World for July 4, 1972:

The bottom had reportedly dropped out of the used-brick market in Lawrence as several local residents had been indulging in a “brick scavenging craze” at the downtown excavation site. Old local bricks, such as those stamped with “Lawrence, Kansas” or variations on “Lawrence Vitrified Brick Co.,” or even the rare “Don’t Spit on Sidewalk” brick, were among the types prized by local collectors. Some of these could still be found at local flea markets, but people appeared to prefer the pick-your-own method as the downtown improvement project had uncovered the red brick street laid out in 1899. The sudden availability of free old bricks had gone to the heads of local patio-makers and amateur wall-builders, some of whom had lost all sense of proportion by appropriating the components of a brick sidewalk that had never been intended as part of the excavation. An article in today’s Journal-World described Lawrence in its brick-manufacturing heyday, with several such plants in the city. A well-known brick yard with a two-story factory building had been located on north Alabama Street where the VFW building now sits.