It is said that the New Testament records Jesus speaking more on the subject of wealth and want than any other.
In one of those instances - responding directly to someone who had asked Him to arbitrate between brothers about an inheritance - He told a story about a rich man who planned to build bigger and better and store up his wealth and retire, but God called him a fool ... required his life of him that night ... and asked him who would get all his accumulated things. Then Jesus said: "This is how it will be with anyone who stores up things for himself but is not rich toward God." (Luke 12:21)
In Matthew 6, His meaning is clear: If you're too much invested in clothes or cars or cash, you need to be aware that there are things like moths and rust and thieves. It's a topsy-turvy concept: treasures gained by giving away; wealth accumulated by divestiture; richness toward God through poverty of spirit.
And when it's demonstrated by a widow giving the tiny amount she has, the God whom she worships praises her generosity.