Ditto on the Microsoft site. They have THOUSANDS of pieces of art and some great search tools to find them. For bingo, they only had 4 pieces, but "turkey" gets you 21 DOZEN choices.
I just did Halloween bingo cards last week for my Brownie Troop. I printed the cards off crayola.com. You might want to check and see if they have anything for Thanksgiving. They had 5 different sheets- you might have to cake some of your own if you want all different cards.