You may want to grab the $2/1 Purina Beneful Dog food coupon (with no size restrictions!) from the 4/29 SmartSource insert and head over to your local Walmart to be able to get a possible $1 moneymaker on the trial size bags of Purina Beneful!
You can then, per Walmart's coupon policy use the overage towards other items in your cart.
Keep in mind that some stores may not carry this size, so you may either want to call ahead, or stop while you were going to be out anyways.
Purina Beneful Dog Food Trial Size $1.00 Use the $2/1 Purina Beneful Dog Food, exp. 5/27/12 (SS 04/29/12) FInal price: free + $1 overage towards other items in your cart!
(Thanks, I Heart the Mart!)