I would feel just rotten on the inside for a long time if I kept any of the money or jewels.

Back in Ohio I found this guys planner in a parking lot... it had all his credit cards,  small amount of cash, ID, dumbass even had his SS card in there.  Well, he was black so using the ID was out of the question so I drove to the address, not too deep in the hood but definitely not a white family for blocks.  When I knocked on the door this woman opened and gave me this WTF do you want? look and greeting... I held back the urge say, "whoops wrong house" and walk away and showed her the planner.  I thought she was going to faint, she looked so damn surprised and started thanking me over and over again.  She then yelled for her husband... demanded he thank me and then started tearing into his ass!!   AHAHAH!!! It was classic....  "I'm sorry, baby..."

Dumb motherfucker.

On a more practical level.

The bag belongs to the wife of a wealthy California industrialist.  Unfortunately, earlier that morning a thief broke into their Tiburon peninsula home, murdered the wife, grabbed what jewels, valuables and cash he could lay his hands on, stuffed in into the nearest purse and beat it.  The thief then handed it off to his girlfriend, to account for carrying a bag and tells her to meet him with it in the park after he ditches the getaway car.  The gf puts the bag down on the park bench and waits.  For one reason or another, possibly cold feet, she leaves the park and leaves the bag on the bench.  Joe Fafoofnick is walking by in the park, sees the bag.  He looks into it and sees that it is valuable.  Pulled in two directions by morality and greed, he succumbs to greed and takes it home and hides it in his garage.

A few years later, his wife finds it and decides the baubles are pretty and wears one.  While shopping, it is spotted by an undercover police officer and recognized as one of the unique gems taken in the murder/robbery.  She is taken in and questioned; it follows shortly that her husband is questioned and subsequently charged with murder.  Though the husband ostensibly had a witness tht he was at work at the time of the robbery/murder, it never came out at the trial because of all the hullaballoo surrounding the famous victim.  

Joe now resides in San Quentin awaiting execution.

If one doesn't understand that taking it is stealing, and "Thou shalt not steal" is too complicated, look at the practicalities of the situation.   With minor changes, the believability of which depends on hurried typing and a tired brain, this is how Bruno Hauptmann was executed.