Here are a few places to look Grocery coupons:

Sales circulars can usually be found within the store. Also some supermarkets have little machines in the ailes where you can snag free coupons.

Sunday Newspapers have coupon inserts. Buy 3 newspapers at a time.

The internet has tons of websites that allow you to print free coupons. Coupon Mom is my favorite.

The problem with these examples is you have to factor in the amount of time you spend looking for, clipping and printing coupons. It is not worth it to spend hours collecting coupons and saving only a few bucks. Here are some better examples:

Supermarket receipts may have coupons on the back.

Grocery items may have coupons attached to them.

Join a coupon train.

and my favorite...

On eBay you can purchase multiple coupons that are already clipped!