I actually have a previous answer on that very subject! I will paste it below:

It's fairly common for filmed representations of Mary Stuart to present her time of imprisonment as her truly in a prison, but that's misleading.

When Queen Mary fled Scotland in 1568, she landed in Cumberland and was taken by the county's deputy governor to Carlisle Castle, where she was first installed as a guest but still put under guard - it was not at all clear what Queen Elizabeth would want done with her. It was decided, in a compromise between Elizabeth and her cabinet, that Mary should be investigated for her part in Bothwell's conspiracy to murder her husband, Lord Darnley, and then she could be accepted properly into England if she were found innocent. As a result, she was deemed most certainly a prisoner, though still a very distinguished one. She had only two women to wait on her (a far cry from the full staff expected by a queen), was kept in rooms with barred windows, and was not allowed out riding, although she still went on foot under a large guard.

The noblemen of both England and Scotland wanted to find Mary guilty and get her off the political stage, and letters she had supposedly written proving her to have played a part in Darnley's death were duly "found". At the same time, popular sentiment in both countries was playing in her favor, so she was soon moved south to Bolton Castle in Yorkshire, the home of Lord and Lady Scrope. This was a much more distinguished imprisonment, with a larger budget and trips out hunting, although assembling a suitably royal wardrobe seems to have been difficult (unsurprising, given that clothing/fabric cost so much more then, comparatively); she also had Mary Seton, one of her long-time ladies-in-waiting, as well as her own staff of servants, and she was on good terms with Lady Scrope.

The trial occurred at the end of 1568 without Mary's actual presence, and while there was plenty of "proof" of her guilt in the letters and the evidence given by her half-brother, the Earl of Moray, Elizabeth was reluctant to actually pass a sentence on her cousin and fellow queen, so she declined to pronounce her officially innocent or guilty. But in effect it was clear that Mary was now considered a proper prisoner: she was put in the keeping of the Earl and Countess of Shrewsbury for the indefinite long term, and sent farther away from Scotland, to the dilapidated, damp, and drafty Tutbury Castle in Staffordshire. Still, she had around fifty male and female servants - including a cook and physician - and ten horses, and ate like a queen, even if the earl had to pay for it all himself when Elizabeth failed to keep up the promised allowance of £52/week (a staggering but still insufficient sum at the time); Mary technically was also supposed to be receiving money from France for her dowry, but that was also not often provided. Mary was permitted to be moved to the much grander Sheffield Castle, where she was still constantly under guard, but proceeded to live magnificently, with lavish furniture and an immense, regal wardrobe. As at Bolton Castle, the wife of her captor (the wonderful Bess of Hardwick, whose daughter was actually Mary's sister-in-law) became a good friend as well. You're interested in her food, so I'll quote from Kate Williams's biography there:

She dined off silver dishes and expected two courses at meals, both with a selection of sixteen dishes from which she would choose, washed down with crystal glasses of wine, along with plentiful bread, salad and fruit. A typical menu might be soup, with meats such as veal, chicken, beef, mutton, duck and rabbit, followed by substantial dishes of pheasant, lamb, quails and a baked tart. Her ladies were allowed nine dishes per course, the secretaries six or seven, so there was a lot of wasted food. Mary lived in such grandeur that her court was second only to Elizabeth’s.

While Mary was briefly given over to the Earl Huntingdon along with all of her servants as the situation rapidly deteriorated in 1569-1570, she would spend about sixteen years in the custody of the Earl and Countess of Shrewsbury in this fashion. However, by 1584, Bess and Mary had fallen out, with Bess resenting Mary's drain on her family's finances and her husband's attention, and Mary telling Elizabeth that Bess was wildly slandering her with demeaning sexual gossip. As a result, Mary - now in terrible health - was passed to Sir Ralph Sadler and then Sir Amyas Paulet, and returned to the uncomfortable, inappropriate Tutbury Castle, where she could not maintain her lifestyle at the same level of luxury. She was still allowed her large staff, but everything else was strictly reduced, and Paulet made it clear that she now had no more expectations of privacy in her letters, belongings, or servants. She would be moved several more times before her execution in 1587, never with the same level of freedom and splendor as she had previously.

Did she paint?

The thing that made me respond to this post was actually this specific question. While painting is now the popular "if only I had time" form of creativity, in the sixteenth century an aristocratic woman with no children to supervise and no estates to manage would turn instead to embroidery, and Mary was no exception - one of Elizabeth's agents who visited her when she was with the Earl of Shrewsbury noted that she said that "all the day she wrought with her needle and that the diversity of colours made the time seem less tedious". Not only was it an art she could use to brighten her life and pass the time with Bess, as well as a craft used to create presents to give people to affirm their relationships, it could easily be used to create politically symbolic images to bolster her claims as queen. For instance, she embroidered a satin petticoat for Elizabeth combining Scottish thistles and English flowers, and the work she created with Bess contains many motifs said to relate to her situation. Antonia Fraser describes several of them:

One panel consisted of a lodestone turning towards a pole and the name MARIA STUART turning into the anagram SA VERTUE M’ATTIRE which Drummond preferred to the other anagram of her name VERITAS ARMATA. A phoenix in flames was said to be the emblem of Mary’s mother, Mary of Guise, and the words accompanying the device were that now famous motto of Mary Stuart: EN MA FIN MON COMMENCEMENT. About the same date Cecil’s emissary White noticed this motto also embroidered on Queen Mary’s cloth of state. Some emblems referred to Queen Mary’s past – the crescent moon and the motto DONEC TOTUM IMPLEAT ORBEM for Henry II, the salamander for King Francis I. Others alluded more directly to Mary’s recent fortunes and her future hopes from Elizabeth – for example two women upon the wheels of fortune, one holding a lance, and the other a cornucopia with the motto FORTINAE COMITES. A lioness with a whelp and the motto UNUM QUIDEM SED LEONEM referred to Mary and her son James.