what is digging up my new plants?

[dlhein]

Has anyone ever had this problem? I planted three corydalis lutea about 2' apart and another one about 8' from those. The next morning one of the three together and the lone one 8' away were out of the ground laying next to their holes. The dirt was all piled around the holes. It looked like someone was neatly getting ready to plant them! And I couldn't see that any of the plants were eaten and no animal evidence in the vicinity. I have planted a lot of plants back there and this has never happened. Has anyone you ever heard of this? And why just those two both times and not the other two? I am so baffled by this. What should I do? Yesterday after replanting them I sprinkled some Milorganite about in a circle about a foot away from each one because I do that to deter deer (which we don't have a major problem with) from my hostas just to be safe and it seems to work. I know I probably shouldn't fertilize a plant that soon, but it was just a small amount far from the plant. And this morning the same two were dug up in exactly the same way again! It almost looks like a person did it, but I can't imagine who would. What should I do? I'm afraid if I move them to another location whatever is doing this will mess with the two that haven't been messed with yet. Thank you.

[Tigger]

Squirrels. I think they do things like this for fun.