There are 15 words that start with 'yeas'.
| yeas | yeast | yeasts | 
| yeasty | yeasted | yeasayer | 
| yeastier | yeastily | yeasting | 
| yeasayers | yeastiest | yeastless | 
| yeastlike | yeastiness | yeastinesses | 
Note: These 15 words that start with 'yeas' are found from the USA & Canada version of the tournament Scrabble word list.