It is legal so long as the zoning for your mom's business permits the business activity(ies) you intend to do: that is, if, for example, her business is not zoned to allow sales of these sorts of things, you can't; but if items like you describe can be sold under her zoning, you can do this. If you don't know the zoning, you can check at town or city hall, in the clerk's office. If you sell them under your own name but there, the income will be taxable to you; if you sell them under your mom's business's name, it will be taxable to her. Make sure to collect and submit sales tax.