This photo is by Sami Ståhlberg. Sami wins a free month of access to all of my videos and science activities. The question:

I found these in my yard a few years back. What are they?

These are pupae, probably from a large moth, probably a kind of sphinx or hawk moth. The caterpillar crawls under the leaf litter, and sometimes into the dirt before it pupates, so it is not uncommon to find them as you dig in the garden. Thanks Sami!