Hi Diae!

I have fostered for this group. One thing to remember is that if you are fostering you can get any age on short notice, so it is good to have a variety of basic toys that can span age groups.

I recommend:
outside - balls, sand toys, bubbles
art supplies - crayons, markers, papers, safety scissors, glue sticks
play dough with toys like cookie cutters, rollers, and such (or better yet, have a good play dough recipe ready and make your own)
books - choose timeless stories, as well as a board book or two
trucks and cars
blocks like Brio
doll with bottle, clothes, and blanket

That is lots to start. That will keep your kids going long enough for you to get more, without taking over your house with things that you don't need yet. For example, in four years of fostering we never had a child over age two. If your youngest is six, you don't watn to be stuck with a pile of baby toys.

Having said that, let your friends and family know what you are doing and never turn down free toys or clothes!