After a lot of searching, I found the most gorgeous Baby Cot sheets!
Crib Sheets White - Bella Baby, Award Winning Baby Shop
6PCS Cartton Car Baby bedding sets Bed set,cot Bed linen for children Nursery Bedding for Boys (4bumpers+sheet+pillow cover)|baby bedding set| bedding setcot bed - AliExpress
Nursery & Baby Furniture | Baby Bedding for Cots | Smyths Toys UK
baby cot sheet sets photo,images & pictures on Alibaba
Organic Cotton Olly Baby Cot Sheet White | Sheridan Australia