Pappy's Pony

At 22 years old Pappy's Pony is one of the senior mares of the current Assateague herd. Her sire was the brown tobiano Witch Doctor and her dam was the flaxen chestnut Island Star. Her old identification number was B18 and her first several foals were sold at the auction under that number. Two of her foals have been kept for the herd, the short lived Kelly's Raven Moon and current herd member Barbara's Tasi.

Pappy is a solid bay which means she has black and agouti. Agouti tells her black to stay on her points. She has had 4 black foals over the years which tells us she only has one copy of agouti. If she had two she couldn't have had any black foals.
https://www.thecolorfulchincoteague.com/bay.html

Her dam was a chestnut so Pappy carries recessive chestnut. If that wasn't known her 6 chestnut foals would have told us that. In order to get a chestnut foal both parents must be or carry chestnut.
https://www.thecolorfulchincoteague.com/chestnut.html

Pappy doesn't have any white markings so she visually doesn't show any signs of having a white pattern. One of her daughters with Surfer's Riptide has White 20 and is the only Chincoteague tested to have it thus far. W20 can sometimes be found on solid horses so perhaps it came from Pappy!
https://www.thecolorfulchincoteague.com/white20.html