The wife is a serious board gamer, so I've played a whole bunch. She tells me that
boardgamegeek.com is *the* place to go for reviews and recommendations. That said, a few of my favorites:
Chess - For those of us that prefer strategy to shiny bits of plastic ;)
Mr Jack - we've got the travel version. Great two player game, reminds me of chess in that it takes a lot of planning and forethought to play well.
Hive - still not sure I love it, but it's interesting and portable
Fluxx - just kind of silly fun. Though some of the expansions (eg, Zombies) seem to lead to a near-endless game.
Cards Against Humanity - but only if you're drinking. And definitely not with your mother (yes, I did that once. And she played the "Oedipus Complex" card...)
Pandemic - A cooperative game, so it's good if you have some non-gamers or non-competitive types in the group (like your mom)
Traders of Carthage - a good optimization game. Plays well even with just two players.
Of course, if you want to get all Mustachian about it, just get a deck of cards. You can play dozens (hundreds?) of games with just that one deck. Personally, I'm a fan of euchre or spades if you can get four players.