Funny thing is my dad thought he fount £20 on the streets but he was behind me and I never put the money in right in my pocket and it fell out, hence how he thought he fount it. He had to give it back to me though.
I once found a purse containing around £50, a credit card and a cheque book (this was in the days when you could use a TSB credit card as a cheque guarantee card and when £50 was worth about £250 in today's money). I took it to the local TSB who returned it to its owner. She seemed rather keen to show her gratitude - I had to tell her I had a headache.
£200. I went swimming once and when I went to put my stuff in the locker there was a wallet in there with £200 cash in it. I handed it in which was down right decent of me.