All uncanceled certificates of purchase and patents issued prior to May 20, 1907, and payments made prior to May 20, 1907, for any lands as swamp and overflowed lands, which belong to any of the classes described in Section 7601, whether or not such lands were segregated or sectionized, are for all purposes valid, and have the same force and effect as if such lands had been at all times subject to sale as swamp and overflowed lands.