The phrase "a poor thing but mine own" is often used to refer to something that may not be the best, but it belongs to the speaker and holds sentimental value. Synonyms for this phrase include "a humble possession," "a cherished but humble item," or "a sentimental trifle." These phrases emphasize the love and attachment the speaker has towards the object, regardless of its perceived value or status. Other phrases such as "a modest treasure," or "a modest memento," can also be used to describe something that may not be grand, but holds personal significance to the speaker. Despite being of small worth, these items hold a special place in the speaker's heart.