Some dirt from the plot I cleared of grass for the garden, some compost mix a firend of mine made, some "store bought" topsoil, some potting soil, some hummus mix froma bag of that I bought... ...probably some powdered dried leaves from a tree in my yard. Maybe I dug up a squirrel stash, put it in the pot, and didn't even know it.
I know what you mean about all manner of stuff popping up from bagged topsoil. One "bargain" bag I used is a likely suspect in a mini-plague of some sort of wee weeds that grew in among the turnips I planted... ...weird.
Concerning sunflower nutrition - one site I found declares them to be "The Super Food"
An interesting note is the apparent protien content, among other things, of course.
Considering that sunflower seeds are almost 25% protein, it is no wonder that sunflower sprouts and greens, grown from these seeds, are nutritional super foods with few rivals. A mere 3.5 ounces of sprouted seeds contains a whopping 22.78 grams of protein! The same amount of chicken breast meat contains just slightly more protein at 26.25 grams. Sunflower sprouts and greens are a rich source of vitamins A, B complex, D, and E and minerals including calcium, copper, iron, magnesium, potassium, phosphorus and zinc.
In addition to these vitamins and minerals, sunflower sprouts and greens are a rich source of lecithin which helps break down fatty acids into an easily digestible water soluble form, and chlorophyll which benefits many functions within the body, including building blood supply, revitalizing tissue, calming inflammation, activating enzymes, and deodorizing the body. But if they are this good for you, they must taste bad? Wrong! Sunflower greens are considered a delicacy among gourmets and are known for a crisp nutty flavor.