A 4" plant that fits in a small ceramic planter. There are several that thrive in fluorescent lighting and require very little attention. A little ponytail palm, also called elephant foot has tons of personality and likes to be watered about every 4 to 3 weeks. A snake plant is popular these days. I also bought two 4" "exotic angel" plants by Costa Farms at Walmart and they do great with water about once a week or two. Some large coffee mugs work perfectly as a planter. I leave the plants in the containers and remove from the ceramic planter to water so they drain. Also, all of these are very slow growing so they'll stay petite perfectly for the desk. You can get a little package of moss to cover the top so the entire ensemble looks pulled together. I read the Dollar Tree has the moss. The 4" plants are around $3. A mug for $6 or $8 and you have a lovely gift for $10 to $12.
A 4 x 4 ceramic tile as a coaster, you can glue little pads on all 4 corners if you like. Fill a coffee mug with snacks, put a small gift certificate (perhaps Office Depot or Staples) in a mug or a card, office supplies-stapler, tape, pens, post-it notes.
Cynthia....Use a pencil box or soup can (covered with contact paper or mod podge and 1 ply napkin...add flowers of your choice and change seasonally.
Cynthia, here are a few ideas. I hope this helps.