Has anyone done this, sowing directly into the flower bed?

Last year I purchased plants (a first) & loved how they did under a large tree. Enlarged the bed, but will cost a fortune for that many plants. Last week I saw a large box of seed at WM. I'm in Z6 & past hard freeze so, per the box, I can plant now.

I won't need all the seed....can I store them to use the rest next year? If so, are there special ways to store them or will placing them in a cool, dry place be sufficient?

Any help is greatly appreciated.