There are 12 words that start with 'yest'.
| yester | yestern | yestreen | 
| yesterday | yestereve | yestreens | 
| yesterdays | yestereves | yesteryear | 
| yesternight | yesteryears | yesternights | 
Note: These 12 words that start with 'yest' are found from the USA & Canada version of the tournament Scrabble word list.