Rite aid has a promotion where you get a $10 gas card for spending $30 on qualifying products. Generally their prices are not great, but looking at this week's circular I saw a couple of qualifying items with decent prices.
24 pack of Nestlé water bottles for 2.99
Various cereal boxes are buy one get one free (no price given, but can't be too bad when the normal price is cut in half).
Also, hellmans mayonnaise, 2 for $6
Especially if you buy with a amex blue cash card and get 3 or 5 or 6 percent cash back on top of the gas card
Limit 2 gas cards per week, and promotion end may 2nd (apparently it has been around since the last month).