The purse symbolizes desperation of the boy because Mrs.LBWJ has no save place to put her bag but Roger is so desperate for money that hes gonna take whatever he can get.
The money symbolizes trust because after Roger steals her purse she starts to trust him and even gives him his money for blue suede and that shows she trusts him enough to go get what he wants.
The blue suede shows symbolizes that he is struggling and poor. He doesn't know right from wrong and since he is struggling he attempts to steal her purse to get money for his shoes. After he tells her that he just wants his blue shoes she understands because they are both struggling to get the life that they want so she just gives Roger some money for his shoes and they both go on with their lives