Is there a way to buy weed seeds? (Not Pot)?

Bird seed is basically weeds in seed form. 

weed is for smoking not planting

You don't need "weed" seeds. You need a ground cover or a plant that spreads quickly to keep soil from eroding. Anti-erosion plants include alfalfa, clover, sweet pea, crownvetch, grasses, or vincas--you can buy these seeds in bulk and they also enrich the soil. Go to a farm-supply store or look online. 

It's good to see that our country-living, 'tard kids are well up to the task of coping with life's vicissitudes. Hang on in there. You're doing well. Doing great!

You are not the only person who has the problem. Check with your county agent or a local farm supply store for what the solution is.  There is something good that will grow there.  How about clover?

Don't be too quick with that solution.

In the U.S., you should consult with your County Agricultural Extension Agent, who knows your climate and soil, and can advise you best on pasture management.

There's going to be a better solution than just letting weeds grow.

I am sure there is somewhere