If you've ever spent a beach day at Dane St Beach here in Beverly, then perhaps you've discovered this little brook way on the north side of the cove.

And if you're like me, maybe you've wondered "huh, I wonder what they call this brook?". Turns out the answer is not forthcoming, and has led me down a rabbit hole of trying to find the names of Beverly's coves, points, creeks, and brooks. Aspirationally I hope to make this into a larger series on place names in Beverly, but we'll start for now with this one little brook.
For historic place names in Beverly, Sidney Perley's Beverly in 1700 - part of The Historical Collections of the Essex Institute, volume LV - turns out to be a treasure trove! On map no. 4, we can see the brook in question here:

According to Perley, the brook had been call Cedar Stand Brook in 1708, and Sallows Brook by the time of the publication in 1919. It's worth noting that according to Perley, Mackerel Cove (where Dane St Beach is located) was called Cedar Stand Cove between at least the years 1698 and 1919.
After 1919 it was difficult to find any map that labeled the brook with a name, and I was only able to find an official recent name in the form of a municipal stormwater catchment map:


Finally some answers! We can now confidently call this little waterway Lawrence Street Brook, named presumably for Lawrence Street which the brook parallels.
This catchment map also shows us that the brook drains both Kellehers Pond and the brook in Sally Milligan Park (called "The Mackerel River" on some trail maps).
Course Description

With the development of Beverly into a City and Suburb, much of this brook's course has been buried in stormdrains and culverts, re-emerging every now and then in people's backyards before diving back underground. On the map above, I've traced the brook's major channels, all of which run above ground for at least a portion of their length.
The three main sources of the brook appear to be the wetlands behind Hurd Stadium, the so-called "Mackerel River" which runs through Sally Milligan park on Snake Hill, and the outlet of Kellehers Pond.
The Mackerel River leg begins in the ponds and wetlands behind the Greater Beverly YMCA, before crossing Essex St and snaking it's way through Sally Milligan park. From here it parallels Cross Ln before going underground at the intersection of Cross St and Cross Ln. It then runs beneath Lothrop St before re-emerging near the intersection of Bisson and Lawrence St.
The Kellehers Pond leg begins in the drainage pond behind the parking lot of Hannah Elementary, before spilling into Kelleher's Pond. It exits the pond through a spillway near Essex St and continues underground. It emerges briefly at the railroad crossing with Essex St before continuing beneath Lakeshore Ave for a long stretch. It emerges again on the south side of Lakeshore Ave, and continues on private property both above and below ground before joining the main channel beneath Lothrop St at its intersection with Corning St.
The Hurd Stadium wetlands leg run a short distance above ground on private property before joining the main channel beneath Lothrop St next to Temple B'nai.
After emerging from Lawrence St, it stays above ground on private property for the remainder of its course before finally spilling from a stone rill into the ocean at Dane St Beach.
GZ will place you overlooking the brook on Hale St, on what was called "Sallow's Bridge" in 1730. BYOP