A couple of jars of baby food when ds2 was weaning. I put them under the pram apron for some reason 
One if the DC (can't remember which) 'stole' a bag of seashells on a day trip. I didn't notice until I was folding the pushchair up to get back on the coach. We didn't have time to go back, and actually wouldn't have known which shop they were from anyway.
2 exercise bikes from argos. They were left on my neighbours doorstep by the delivery guy. 3 hours later it was raining and they were still there so I dragged them to my house. (They were heavy!) Told the dc to check if they were for Dave or Mark and write them a note to tell them we had them. They were for a name we didn't recognise who lived at next doors number but 2 streets away. I phoned argos. They refused to come and collect them from me and said I had to take them back to a store. I don't drive so that couldn't happen. I phoned again the next day and asked them to let the customer know I had them. They refused and said replacements had been sent already. I phoned a couple more times and they continued to refuse to come and collect them. So I kept them.