Hell yeah! at that rate there will no hamsters left to coo...pet, yes i said pet, not cook, stop staring at me!!!

My best guess:

The dull answer is, dryads are fey so they mostly spontaneously arise in oaks in very old forests. They are exclusively female so they do not have any mating habits per se. They are the souls of the trees.

Dryads occassionally take fancies to other creatures and being fey can pretty much 'enjoy the company' of anything. As fey are magical creatures, there is a reasonable chance the dryad and her swain could interbreed. The child would either be a dryad (if the dad is another kind of fey such as a satyr) who would be born at the same time as an oak sapling germinates from an acorn off the parent tree. The oak/dryad soul-link starts at conception.

If daddy isn't fey (and he could be anything give the general free spirited nature of dryads) then the child is half-fey. He or she would not be bound to a tree but would likely feel an affinity to nature. Elves are the most likely candidates for relationships with dryads as they share similar outlooks and livespans but other crosses are entirely possible.

The Dungeon and Dragons open source supplement 'Bastards and Bloodlines' describes a half-dryad as a 'Spring Child' and goes on to state that dryads are affectionate mothers but find it difficult to relate to their mixed heritage children. There is little to a dryad's life other than her tie to her oak and the woods beyond so the 'outside world' and its concerns are foriegn to her. That makes it difficult to half-dryads to share their experiences with their mothers as dryads cannot stray far from their trees.

@Charity, in my oppinion, a dryad would mature at the same rate as her tree. They share a mystical bound; the tree anchors the fey spirit to the physical world and therefore would govern the growth of the dryad's physical body. So, as an oak is mature at around twenty years of age, that's about when a dryad would be physically adult.

If a dryad's child is a dryad herself if the father was fey and so would mature at the same rate as Mom. If Dad was not fey, the child would mature more or less at the same rate as he does but would likely live in good health for longer. The fey blood loses is intensity quickly (half-fey are mortal) but takes a long time to fade out completely.

Dryads are very easy going mothers. They have few concerns beyond the forest so in all likelihood, Dad would do most of the parent if the child isn't a dryad herself. Folklore tells of rangers and travellers charmed by dryads who spend their days protecting her oak. It would not be unreasonable to assume, such an enchanted person would also take care of the dryad's children.

Given Mom can go a reasonable distance from her tree and is in tune with the 'cycles of nature' she could easily take one of her tree's acorns away from her tree. She would likely find a place of natural beauty to make her daughter's home or perhaps a druid's grove.