Saint Agnes of Rome, a 4th-century saint.

Who she was:

A young girl, around 12 or 13 years old, who refused to marry, stating she could have no spouse but Jesus Christ. 

Her story:

She was martyred for her Christian faith during the Roman Emperor Diocletian's reign, likely on January 21, 304 AD. 

Veneration:

She is venerated as a saint in the Roman Catholic, Eastern Orthodox, Anglican, and Lutheran churches. 

Symbols:

She is often depicted with a lamb, as her name resembles the Latin word for "lamb" (agnus), and with a palm branch, a symbol of martyrdom. 

Patronage:

She is the patron saint of chastity, gardeners, girls, and engaged couples.