Proprietary, 1871, 3¢ blue & black, trial color plate proof on bond paper, gummed (Scott RB3TC5a), lower left corner sheet margin block of 24, o.g., never hinged (!), Extremely Fine.
Scott $1,440 as sgls. (Image)

Estimate $500-750

Proprietary, 1875, 1¢ to 6¢ plate proofs on India paper (Scott RB11P3//RB17P3 etc), also a 2¢ 3rd issue and an Official Seal, all mounted on a large card, Very Fine, ex Green.
Scott $670. (Image)

Estimate $200-300