Microgreens are really just overgrown sprouts, and can be grown from any clean seed for any kind of green that you'd normally eat mature, and a few that you would not! They can be grown like sprouts, with just water, or in soil. Either way, they are allowed to get a little larger than sprouts, but usually not fully into the secondary leaf stage. Unlike sprouts, Microgreens are typically clipped rather than tossed in roots and all. They'll grow in a sunny window just fine. You can find Microgreen mixes and seeds in most major seed supplier catalogs and websites now.