How about a nice vase with real or artifical flowers with a nice poem/letter attached to it, or a picture of u in a frame with a letter/poem over the picture or something that your mother really needs & will enjoy. There are tons of things to get the best is something that she will enjoy & will remember that you gave it to her.
are u the first married? – the standards go up a bit when you are hosting the new marrieds-so maybe – a set of guest towels/bath towels/bathroom accessories/guestroom accessories, nice serving stuff for serving some kugel/fruit, tray/mini leichter, – I know it sounds like the gift is for you, but these are things she will need/want. Good luck and MAZEL TOV!