You can try making her some homemade flowers for mother's day. And the great thing about it is that you get to choose the colors of the flowers and you can use any supplies at home and be creative, so you don't have to buy anything. As of you trying to get her a gift next year, here is a suggestion : try saving up some changes and dollars starting from now. Every time you get few changes or dollars, put it in your piggy bank, box, or bag and put it aside somewhere secluded for your mother. So that when the next mother's day come, you would have some money to buy her a gift for mother's day and even enough to buy her something for her birthday too ^_^.
P.S., The reason for saying putting the saved money in a secluded place is so that you would be tempted to take the money out
.