Many Labrador Retriever rescues, including Golden Gate Labrador Retriever Rescue and Lucky Lab Rescue, offer yellow dogs. However, their supply is contingent on whatever dogs have recently been placed with the rescue, so there is never any guarantee of getting a Labrador of a particular color.
Rescues are groups that take in homeless pets, animals from shelters and animal control agencies, and pets directly from owners who can no longer care for them. Many rescues specialize in particular breeds, such as Labrador Retrievers.
While it is possible to pick up a dog of a particular breed from these specialty rescues, there is never a guarantee that a particular kind of dog within the breed is available. Yellow is one of only three coat colors in this breed and one of the most common.