I'm not quite sure what a "Lunchable" is, but I know that Oscar Mayer produces them, and I'm pretty sure you can eat them. I also know that back in 2004 or so, they came in boxes, which also included a Spidey trading card. I'm guessing one card per box, since that seems to be the traditional thing to do.
The trading cards aren't actually regular "trading card" size, and strictly speaking they're not "card". These cards have credit-card dimensions, and are made out of thin, flexible plastic, more like paper-thickness rather than card. Each card has a transparent area in the middle, but the remainder of the front of the card forms an excellent lenticular picture which, as you tilt the card up and down will show about six or seven sequential frames of an action sequence. The lenticular sequences are top-rate quality.
According to the instructions on the back of the card, the transparent area forms a "Spider-Sense Decoder". You're supposed to lay the card flat on the back of the Lunchables box, and move it around to find hidden letters, which form a special code you can type in at www.lunchables.com to unlock more "Spider-Man Action".
There are six cards in the set. The quality of these cards, the fact that you need to go buying boxes to get them, and the coolness factor of the 2004 movie add up to make these a instant classic collectible. These fellers belong in any serious Spider-Man trading card collection.