For the lowest recoiling factory loads, the 148 grain Wadcutter load is your best bet.

If you want to buy ammo at Wal-Mart or just about any local gunshop, any manufacturer's 130 gr. full metal jacket round will be low recoil too (700 fps for the wadcutter, 770 fps for the 130gr FMJ). All the major brand names make a version of the 130 grain target load. Federal is notably cleaner than Remington/UMC.

Edited to add:
If your local dealer carries MAGTECH brand ammo, he should be able to get their ".38 Special Short" (Catalog #38G). This shoots a lighter, 125 grain bullet at only 686 fps. Range will be very limited, but for short range shooting it'll be your lightest load.

These cartridge are shorter than the standard .38 Special and are intended for cowboy action shootings were power isn't needed.

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BillCA in CA (Unfortunately)