I have gathered all of mine from swaps here on the board.
F8's would be handy :D I wanted a variety of animals, objects, foods, etc.... I was not just looking for juvenile prints, as older kids/adults can get a kick out of these too.
Also, I was not looking necessarily for gender specific prints.
Maybe packs with juvenile fabrics (up to age 5?) and another with all others?
Most of the swaps here have been for 5" squares... so maybe keep that in mind when offering the fabrics... it seems to be a standard size liked.