Peanut butter and honey sandwiches are a regular lunch item for me. Occasionally I switch it up and have peanut butter and pickles (the sweet kind). Peanut butter and liverwurst appears on the chart because I'm pretty sure Shaggy from Scooby-Doo mentioned eating such a combination at least once in an early episode. I really didn't expect to get any hits from the last item listed. I have, on occasion, used the phrase "like a peanut butter and poop sandwich" to describe a mixed blessing that on the whole wasn't much of a blessing. It surprised me to find out that somebody else used the term. I didn't actually look at the results, so maybe they're from me. I don't recall ever using it on the internet, but who knows?
UPDATED to add peanut butter and banana, Elvis's favorite.