This Simple Modern 15oz Journey Travel Mug with Straw is a great Mother's Day idea! It's just $14.99 right now and ships free with Amazon Prime or when you spend $25 or more.
It's vacuum insulated and comes in a lot of colors, but many have sold out. They have other sizes available as well, so if your color isn't available in this size, check the other sizes.
Please note that Amazon pricing can change at any time. This price is accurate as of this posting. Always check prices before ordering. Find more Amazon deals here or sign up to try Amazon Prime 30-Day Free Trial.