I know exactly how you felt. I actually used a detector in my grandmother's yard at her lake house, about an hour before we spread her ashes there. It might have seemed insensitive to the rest of the family, but I think they understood I was hoping for a sentimental souvenir. The house dated to the 1930s and I found some Wheaties from that time period, but didn't get the Merc dime I was hoping for.
Near the front door of the house I noticed some tiny blue flowers. They were Forget-me-nots.