Here is a list of parks/locations I've used and work well for Family and Maternity Photography.
Phyllis Rawlinson Park
1715 Leslie St, Richmond Hill, ON L4E 3R7
This is my favourite and most widely used park because of the large size of the park and accessibility to parking. There is hardly any foot traffic other than locals walking their dogs, which makes it an easy place to photograph. There are many options and beautiful nature backdrops at this park: a large pond, boardwalk, barns, trails and open green space. This park is best in Late Spring, Summer and Early Fall (September and Early October).
Sheppard's Bush Conservation Area
Industry St (intersection of Mary St and Industry St.), Aurora, ON L4G 7B3
This park is at its most beautiful in the Winter because of the evergreens, but can also be good for Fall and Summer. There is accessible parking, cute cabins for a rustic feel, a forest, trail, bridge and a beautiful tree-lined pathway.
Eldred King Woodlands
York Regional Forest. ON-48, Whitchurch-Stouffville, ON L4A 7X4
I use this forest almost exclusively for Fall because once the leaves change colour, it is beautiful! There is also a large pond if you are up for a 15 minute walk there from the parking. There is a medium amount of foot traffic and dogs that are left off-leash (though it is not an off-leash park).
Greenwood Conservation Area
2290 Greenwood Rd, Ajax, ON L1T 4S4
Greenwood Conservation Area features some open green space, rustic wooden fence entryway and forest/tall trees. I would recommend this park for Spring, Summer and Fall.
Hollidge Tract Accessible Trail (York Regional Forest)
16389 ON-48, Whitchurch-Stouffville, ON L4A 7X4
This location is beautiful for fall and winter! The trails are groomed to be more accessible.