There is Marbles Yellow and White sold by Burpee and Swallowtail but it is out of stock now. Burpee is more expensive. Swallowtail also has a very pretty white called Fairy Trumpets. I never grew either but the pictures are nice.
https://www.swallowtailgardens...
Everwilde sells white, yellow and a few others.
everwilde.com/Four%20O'Clock-Garden-Wildflower-Seeds.html
I have bought from these companies before but if you search four o'clocks by flower color, you will get more options.