Dorothy Gilman's The Elusive Mrs. Pollifax
I think the third Mrs Pollifax book is my favorite so far--the plot works a little better than the others (though they are all fine, I never felt like Mrs Pollifax was doing anything dumb here), there's no period-appropriate racism, there are a bunch of fun new characters, etc. Plus, let me just describe the premise to you: Mrs Pollifax is being sent to Bulgaria (remember, it's 1971 and there's the Cold War), smuggling eight passports IN HER HAT! And of course she randomly befriends a bunch of young hippies and all sorts of mishegas ensues and she GETS THINGS DONE. I LOVE that there is a series about a grandma spy, please someone make this into a Netflix series. It would be a period piece! A lighter version of The Americans! Surely other people would watch that. A/A-.