Final answer:
The detail that foreshadows Elisa's feelings of being trapped in 'The Chrysanthemums' is the description of the Salinas River as a boundary and source of longing for freedom.
Step-by-step explanation:
The detail from the beginning of 'The Chrysanthemums' that foreshadows Elisa's feelings of being trapped is when she looks down the valley and sees the Salinas River. The river symbolizes a boundary and represents Elisa's longing for freedom and escape from her confined life. Steinbeck describes the river as 'grey-flannel fog' and 'dark and mysterious'. This creates a sense of mystery and foreboding, suggesting that Elisa may be trapped and unable to break free.
Learn more about Foreshadowing in literature