On Rte 89 in Layton, UT turn east between mile markers 40 and 42. The actual trail head is directly east of two water towers. However, you can't turn off route 89 right there. You must proceed north until you see the first right hand turn (with no street name). The access road is "East Side Drive". Return south (turn immediately right) on this road to the obvious dirt trail parking area.
If you are heading south on 89, there is a concrete barrier. So you have to make a legal U-turn at Oak Hills Drive (Route 109). After making the U-turn, take the next right.
Access the Bonneville shoreline trail from this parking area. The BST leads to the Adams Cabin and Adams Canyon trails in this immediate area.
Adams trail head is a very popular place and the parking lot is usually pretty full in the evenings. I've counted up to 70 vehicles in the parking lot and along the street. It's especially crowded on Monday Evenings (Local "Family" night) and Wednesday evenings (Local Boy Scout night).
The Adams Canyon Falls trail is most people's destination. From the Adams Canyon trail head, take the switchbacks all the way up the hill. Turn right at the top onto the Bonneville Shoreline Trail. In about 1/4 mile, turn left at the trail junction. Head straight into the canyon through the forest and follow the trail beside the creek. [If you cross a wooden bridge on the Bonneville Shoreline Trail you've gone too far]. The waterfall is 1.3 miles from the Bonneville Shoreline Trail.
Adams Trailhead hooks up with a number of other trails. After proceeding up the the switchbacks (about a 1/2 mile), you will intersect the Bonneville Shoreline Trail. Look for faint trails going straight up the mountain at this junction. This is an unofficial route to Adams cabin.
After the switchbacks: If you turn left at the junction (on Bonneville Shoreline Trail), the Kayscreek/Fernwood trailhead is about 2 miles north. If you turn right at the junction and continue on the Bonneville Shoreline Trail, it will lead to the Kaysville Wilderness Park parking area.