I wouldn't do flea markets. That crowd is looking for deals, not handcrafted art.
You can try puzzles. Freestanding puzzles would work the best. Especially if they're of dog breeds.
Some more ideas that might sell well: bowls, baskets, trivets, boxes, a few portraits (to get custom work), word art, desk name-plates with clever sayings, candle holders, napkin/paper towel holders.