Random pictures being saved to my computer

No they're just going to my images folder

the memory pictures ? sim sees deer for the first time memory , sim eats at the bistro first time new memory created goes to the scrapbook you can turn the memories off go to Options and choose the tab with the two cogwheels choose the option you want for your memories you can turn them off completely you will have to delete the ones in the scrapbook manually if you want them gone alltogether

No they're not memories they're literally just random pictures of random things that have nothing to do with my sims. They're not pictures of my sims, they're just random sim faces and furniture and clothing

Like I opened the game and didn't even select my family, I just quit at the main menu to see what would happen and 500 pictures were saved.

sounds to me like a featured items folder which is in the  pc folders i don't know about mac folders for the sims 3 but that might be the same folder for you just named images  which when deleting images from that folder they regenerate when the game is launched again.hmmm could you take a screenshot of the contents of that folder or at least one or two shots of the images so we can be sure it is featured items upload the image/s to photbucket (which is free ) or some image shareing site you might be a memeber of then copy and paste the link here ...i'm sure caspinwall will take a look as online to advise further

Here's a link to what one of the pictures  are

http://s824.photobucket.com/user/kristenmontes/media/thumb_0cc0ec90_0ccc5e94_2e5c4b6d69e73684_zpse64918a3.png.html?filters[user]=138289852&filters[recent]=1&sort=1&o=0

And here's just a bunch of them in my images folder

http://s824.photobucket.com/user/kristenmontes/media/sims_zps08b583fb.png.html?filters[user]=138289852&filters[recent]=1&sort=1&o=0

Also, they're not being saved to a specific Sims images folder, they're being saved to my images folder of actual images that I've saved 

Well this is very strange isn't it. As rum said, those images definitely look like the ones that normally appear in the "Featured Items" folder, but the OP is saying that they are appearing elsewhere. 

OP - if you look in the "Featured Items" folder, do you see any images in there?  If not then it sounds as though these are the regular images that are generated but for some reason the game is saving them to the wrong place. 

Exactly which folder are these images turning up in?

Yeah the Featured Items folder is empty. Here's a picture of where they are. I have mac 10.8 so it's under All My Files there's an images folder and that's where they are being saved

http://s824.photobucket.com/user/kristenmontes/media/ScreenShot2013-11-24at62438PM_zps3b007dc8.png.html?filters[user]=138289852&filters[recent]=1&sort=1&o=0