You can get dirt anchors at Lowes. They screw into the earth like the anchors that hold telephone pole guy wires. I used them to hold up a basement wall which was falling in. Those had a threaded end which allowed tightening.

Daddy --- I think Mark has one of these in the barn (big auger-looking thing.) Is one enough, do you think, if we attached it to some kind of strapping running around the fridge? Do you think we need a roof if we use one or more of these?

You need two for stability, with connectors fastened into each side of the unit about midway up, and with a couple of stakes at the bottom so it doesn't kick out. A roof will help with stability if it runs water out of the hole. Stacked railroad ties with a roof would be better and almost easier. Digging it into a bank would avoid all kinds of problems.

A roof might help with water falling directly in from the sky, but if there's groundwater penetrating, or runoff from the surrounding higher ground, you'll still have water, and I don't know of an easy way to prevent that issue, and it can get sneaky. Don't know how often you were checking out your root cellar, but I can imagine a scenario where the fridge was slowly starting to rotate forward and the big rainstorm was just the last of a line of smaller movements that led to the collapse.

Rather than go up, I'd think about a solution below, or maybe even to the sides. A pseudo-foundation could work, even as simple as bolting the back of the fridge down to a sturdy piece of plywood set on concrete blocks sunk into the clay. You could also make wider fins and engage the soil to each side of the fridge.

Or you could use anchors.

Hmmm... maybe an email with some sketches is in order...