White Bucks are made from Buckskin, originally from male Brazilian or Chinese deer or elk, nowadays from other materials, like sheepskin or others. They are made from Nubuck leather, which has been sanded on the grain side. This is different from suede leather, which is roughened on the underside of the skin to give it a velvety feel.
White Bucks, are, surprisingly - white, while the tan version is sometimes called "Dirty Bucks." White Bucks classically have red rubber soles and are of the Derby or Blucher design, i.e. open-laced, although I have seen specimen that were closed-laced Brogues or Wingtips.
The history of the White Buck is uncertain, but they appear go back to the 1870s and were tennis shoes originally. They became fashionable around the 1930s, and are still great for special sports occasions, like the tennis or similar, of for lunches or dinners in warmer climes. They work well with seersucker outfits. White Bucks are summer shoes and are mainly for recreational activities (the rubber sole in a shoe not for the rainy days!), although in the Southern USA they have been worn in professional settings with seersucker suits.
The classic red rubber sole.
Woolnough, Richard, The A to Z Book of Menswear, ASIN: B005D3WW2S.
A Brogue version on https://mensstylepro.com/2012/04/16/go-buck-yourself/.