Although not admitted to practice in MD, I would add to Mr. Marcus's comments by noting that as are unlikely to run this business using your own name, you probably need to file a trade name certificate. You should speak to Mr. Marcus as to which state or county agency this is filed with. In addition, make certain you keep separate books and a separate bank account to track income and expenses to properly report sales tax and income tax.

BTW: As innocuous as the rental of beach umbrellas may seem, you should take Mr. Marcus's advice to form an LLC and secure liability insurance just in case a wind takes an umbrella and it flies into someone or a car or window. If forrmed, you will need to file a Certificate of Organization or Formation and secure a Federal Tax Identification Number. As the sole owner, although working through an entity, you will be treated for tax purposes as a sole proprietorship (the LLC will be treated as a "disregarded" entity-not subject to tax, but subject to an annual report fee.