Anyone who has a big basswood tree in their yard knows about the thousands upon thousands of seed pods they dump on the ground every year - while cleaning up the yard I found them everywhere. Another three minutes of interweb research showed me several sources that said the nuts were edible, but too small to be worth collecting. You can see pictured a seed with husk, a split husk, and several of the nuts removed. The other picture shows several basswood nuts with one of the Chinese almonds in the background.
These seeds are constructed similar to walnuts - a husk on the outside with a shelled nut on the inside. Unlike walnuts the husks are hard and woody (instead of black and gross.) Once cracked the nut is inside, with a hard shell covering the meat.
My first thought was to try to eat the whole nut. Not so good, that shell is really too hard to be enjoyable. My next thought was to try to pop them like popcorn. I put them in an egg pan and put another pan on top, swirling them over the flame of the stove. Sure enough some of them cracked with a popping sound. All of them at that point are edible. The shell becomes crisp and crunchy. They would make a nice addition to a trail mix or something.
In the effort of thoroughness I also tried to boil them. I boiled them for 20 minutes (along with a few more Chinese almonds I found.) The shells had softened and could be removed pretty easily, though the work is hardly worth it for the tiny nut meat it yields.
Finally I set up a good collection of them and sat down to watch TV and see how many I could shell. The rate, over 2 hours of work, is approximately a tablespoon per hour of labor. Now I am thinking about ways to construct a powered shelling apparatus...