Can't buy stuff from anywhere !?

Hello, @notpaige. Are you trying to buy things through build mode? To buy books you have to select the bookshelf and select "purchase books". To purchase seeds, you can use a computer or a garden pot. 

I think you can use the D-pad or analog stick to select the number you want, and there's a button you press to actually buy the items. There should be a little guide on your screen, but I'm not sure which button you press on Xbox to buy the items. I hope this helps you. 🤨