We bought this house...

The front yard is grass, and we have plans for the path and flowerbeds. One side yard has lots of dandelions, which we'll probably keep (to make wine!), the other is mostly clover. The back however...
It rained a few weeks ago, and we have foxtails and other pokey weeds, and that's ALL we have. There isn't *any* grass, and this stuff is tall! How how how do we get rid of it all, and get grass, without buying sod? It's about 50' square (maybe more), so sod would have to wait until next year, it's just too expensive. Help!!!
And mil just bought a swingset for ds' birthday. It's small, and I like it, but over this weed stuff??? Ugh...