Yesterday I realized that I had accidentally stolen a grocery item, but I'm thinking that I should just keep it.
Are you really considering theft of a grocery store right now?
I'm just lazy and want to keep it.
It is illegal to steal, even if it was an accident. Don't be lazy and return the item.
I'll just tell them I'm poor and they should give me the money instead.
That's not going to work, and you should just go return the item so that your conscious can be clear. Most people would think of you as a thief if you keep this item.