From day one you've wondered how can you be both a tree hugger and a woodworker, how you can respect nature while also using and working within nature (not roping all of it off limits), as Wendell Berry professes. In Illinois, there is a family-owned and run company called Horigan Urban Forest Products that dries and mills old-growth wood from trees felled in the Midwest's awesome spring tornado season, and summer and fall thunderstorms. There are many sources of wood like this all over the world, and sometimes they're more expensive, but old-growth wood is going to be.
In regards to your breadboard ends: You might be able to get away with what you did depending on how dramatic the humidity difference between seasons is in your area, but in the future, you might want to elongate your dowel holes in the tongue of the joint - all but the center hole. Specifically, you want to put a pin in the center of the table end (no hole elongation) and then elongate the holes on either side - maybe 1/16" to each side of center (it's OK to glue the center like you did). This allows the center pin to keep the board centered (duh) and then allows the table top to grow and shrink across it's width without putting undue stress on the breadboard ends. This is important because wood expands/contracts across it's grain significantly more than it does along it's length, so when you have a joint where end grain meets side grain (as in your breadboard ends) NOT taking this into account can mean that your project disassembles itself - or at least becomes "rickety" as the expansion/contraction cycle loosens the joint. The amount of growth you can expect is determined by wood species, initial moisture content of the wood, and humidity change across seasons. There are online references you can check to see how much you would want to elongate those holes.
The article explains step by step process for making this awesome piece of wooden art. You need are a few pieces of wooden planks, a saw, screws and plates. I must remind you here that a bit of woodworking skill are needed here too. This DIY project is fun and good sport at the same time. It is as easy on the eyes as it is to build one. If you don’t fancy written instructions, a wide variety of videos on the internet are available to help you understand its making.You can easily make the baby cots by joining equal size wooden strips in a specific manner.
There was one crack which required stabilization to prevent further splitting. On an old piece of wood there is nothing more beautiful than a contrasting butterfly inlay to lock the pieces together. Alternatively you could glue and clamp the split, however it is hard to get enough glue into the crack and an inlay looks much better. I used a piece of bloodwood and an inlay jig on my router for the butterfly. This was the first time I've tried inlay and it was very easy. While the butterfly is beautiful & interesting, it acts functionally as 2 opposing wedges to prevent the crack from widening. The last pic shows the finished product.